diff --git a/libp2p/pubsub/floodsub.py b/libp2p/pubsub/floodsub.py
index 14394c71..4b160203 100644
--- a/libp2p/pubsub/floodsub.py
+++ b/libp2p/pubsub/floodsub.py
@@ -35,7 +35,7 @@ class FloodSub(IPubsubRouter):
         :param peer_id: id of peer to remove
         """
 
-    def handle_rpc(self, rpc):
+    async def handle_rpc(self, rpc, sender_peer_id):
         """
         Invoked to process control messages in the RPC envelope.
         It is invoked after subscriptions and payload messages have been processed
@@ -64,6 +64,11 @@ class FloodSub(IPubsubRouter):
         for message in packet.publish:
             decoded_from_id = message.from_id.decode('utf-8')
             if msg_sender == decoded_from_id and msg_sender == str(self.pubsub.host.get_id()):
+                id_in_seen_msgs = (message.seqno, message.from_id)
+
+                if id_in_seen_msgs not in self.pubsub.seen_messages:
+                    self.pubsub.seen_messages[id_in_seen_msgs] = 1
+
                 await self.pubsub.handle_talk(message)
 
             # Deliver to self and peers
@@ -81,7 +86,7 @@ class FloodSub(IPubsubRouter):
                             # Publish the packet
                             await stream.write(new_packet.SerializeToString())
 
-    def join(self, topic):
+    async def join(self, topic):
         """
         Join notifies the router that we want to receive and
         forward messages in a topic. It is invoked after the
@@ -89,7 +94,7 @@ class FloodSub(IPubsubRouter):
         :param topic: topic to join
         """
 
-    def leave(self, topic):
+    async def leave(self, topic):
         """
         Leave notifies the router that we are no longer interested in a topic.
         It is invoked after the unsubscription announcement.
diff --git a/libp2p/pubsub/gossipsub.py b/libp2p/pubsub/gossipsub.py
new file mode 100644
index 00000000..8524ca6c
--- /dev/null
+++ b/libp2p/pubsub/gossipsub.py
@@ -0,0 +1,543 @@
+import random
+import asyncio
+
+from ast import literal_eval
+from .pb import rpc_pb2
+from .pubsub_router_interface import IPubsubRouter
+from .mcache import MessageCache
+
+
+class GossipSub(IPubsubRouter):
+    # pylint: disable=no-member
+    # pylint: disable=too-many-instance-attributes
+    # pylint: disable=too-many-public-methods
+
+    def __init__(self, protocols, degree, degree_low, degree_high, time_to_live, gossip_window=3,
+                 gossip_history=5, heartbeat_interval=120):
+        # pylint: disable=too-many-arguments
+        self.protocols = protocols
+        self.pubsub = None
+
+        # Store target degree, upper degree bound, and lower degree bound
+        self.degree = degree
+        self.degree_high = degree_high
+        self.degree_low = degree_low
+
+        # Store time to live (for topics in fanout)
+        self.time_to_live = time_to_live
+
+        # Create topic --> list of peers mappings
+        self.mesh = {}
+        self.fanout = {}
+
+        # Create topic --> time since last publish map
+        self.time_since_last_publish = {}
+
+        self.peers_gossipsub = []
+        self.peers_floodsub = []
+
+        # Create message cache
+        self.mcache = MessageCache(gossip_window, gossip_history)
+
+        # Create heartbeat timer
+        self.heartbeat_interval = heartbeat_interval
+
+    # Interface functions
+
+    def get_protocols(self):
+        """
+        :return: the list of protocols supported by the router
+        """
+        return self.protocols
+
+    def attach(self, pubsub):
+        """
+        Attach is invoked by the PubSub constructor to attach the router to a
+        freshly initialized PubSub instance.
+        :param pubsub: pubsub instance to attach to
+        """
+        self.pubsub = pubsub
+
+        # Start heartbeat now that we have a pubsub instance
+        # TODO: Start after delay
+        asyncio.ensure_future(self.heartbeat())
+
+    def add_peer(self, peer_id, protocol_id):
+        """
+        Notifies the router that a new peer has been connected
+        :param peer_id: id of peer to add
+        """
+
+        # Add peer to the correct peer list
+        peer_type = GossipSub.get_peer_type(protocol_id)
+        peer_id_str = str(peer_id)
+        if peer_type == "gossip":
+            self.peers_gossipsub.append(peer_id_str)
+        elif peer_type == "flood":
+            self.peers_floodsub.append(peer_id_str)
+
+    def remove_peer(self, peer_id):
+        """
+        Notifies the router that a peer has been disconnected
+        :param peer_id: id of peer to remove
+        """
+        peer_id_str = str(peer_id)
+        self.peers_to_protocol.remove(peer_id_str)
+
+    async def handle_rpc(self, rpc, sender_peer_id):
+        """
+        Invoked to process control messages in the RPC envelope.
+        It is invoked after subscriptions and payload messages have been processed
+        :param rpc: rpc message
+        """
+        control_message = rpc.control
+
+        # Relay each rpc control  to the appropriate handler
+        if control_message.ihave:
+            for ihave in control_message.ihave:
+                await self.handle_ihave(ihave, sender_peer_id)
+        if control_message.iwant:
+            for iwant in control_message.iwant:
+                await self.handle_iwant(iwant, sender_peer_id)
+        if control_message.graft:
+            for graft in control_message.graft:
+                await self.handle_graft(graft, sender_peer_id)
+        if control_message.prune:
+            for prune in control_message.prune:
+                await self.handle_prune(prune, sender_peer_id)
+
+    async def publish(self, sender_peer_id, rpc_message):
+        # pylint: disable=too-many-locals
+        """
+        Invoked to forward a new message that has been validated.
+        """
+
+        packet = rpc_pb2.RPC()
+        packet.ParseFromString(rpc_message)
+        msg_sender = str(sender_peer_id)
+
+        # Deliver to self if self was origin
+        # Note: handle_talk checks if self is subscribed to topics in message
+        for message in packet.publish:
+            # Add RPC message to cache
+            self.mcache.put(message)
+
+            decoded_from_id = message.from_id.decode('utf-8')
+            new_packet = rpc_pb2.RPC()
+            new_packet.publish.extend([message])
+            new_packet_serialized = new_packet.SerializeToString()
+
+            # Deliver to self if needed
+            if msg_sender == decoded_from_id and msg_sender == str(self.pubsub.host.get_id()):
+                id_in_seen_msgs = (message.seqno, message.from_id)
+
+                if id_in_seen_msgs not in self.pubsub.seen_messages:
+                    self.pubsub.seen_messages[id_in_seen_msgs] = 1
+
+                await self.pubsub.handle_talk(message)
+
+            # Deliver to peers
+            for topic in message.topicIDs:
+                # If topic has floodsub peers, deliver to floodsub peers
+                # TODO: This can be done more efficiently. Do it more efficiently.
+                floodsub_peers_in_topic = []
+                if topic in self.pubsub.peer_topics:
+                    for peer in self.pubsub.peer_topics[topic]:
+                        if str(peer) in self.peers_floodsub:
+                            floodsub_peers_in_topic.append(peer)
+
+                await self.deliver_messages_to_peers(floodsub_peers_in_topic, msg_sender,
+                                                     decoded_from_id, new_packet_serialized)
+
+                # If you are subscribed to topic, send to mesh, otherwise send to fanout
+                if topic in self.pubsub.my_topics and topic in self.mesh:
+                    await self.deliver_messages_to_peers(self.mesh[topic], msg_sender,
+                                                         decoded_from_id, new_packet_serialized)
+                else:
+                    # Send to fanout peers
+                    if topic not in self.fanout:
+                        # If no peers in fanout, choose some peers from gossipsub peers in topic
+                        gossipsub_peers_in_topic = [peer for peer in self.pubsub.peer_topics[topic]
+                                                    if peer in self.peers_gossipsub]
+
+                        selected = \
+                            GossipSub.select_from_minus(self.degree, gossipsub_peers_in_topic, [])
+                        self.fanout[topic] = selected
+
+                    # TODO: Is topic DEFINITELY supposed to be in fanout if we are not subscribed?
+                    # I assume there could be short periods between heartbeats where topic may not
+                    # be but we should check that this path gets hit appropriately
+
+                    await self.deliver_messages_to_peers(self.fanout[topic], msg_sender,
+                                                         decoded_from_id, new_packet_serialized)
+
+    async def join(self, topic):
+        # Note: the comments here are the near-exact algorithm description from the spec
+        """
+        Join notifies the router that we want to receive and
+        forward messages in a topic. It is invoked after the
+        subscription announcement
+        :param topic: topic to join
+        """
+        # Create mesh[topic] if it does not yet exist
+        if topic not in self.mesh:
+            self.mesh[topic] = []
+
+        if topic in self.fanout and len(self.fanout[topic]) == self.degree:
+            # If router already has D peers from the fanout peers of a topic
+            # TODO: Do we remove all peers from fanout[topic]?
+
+            # Add them to mesh[topic], and notifies them with a
+            # GRAFT(topic) control message.
+            for peer in self.fanout[topic]:
+                self.mesh[topic].append(peer)
+                await self.emit_graft(topic, peer)
+        else:
+            # Otherwise, if there are less than D peers
+            # (let this number be x) in the fanout for a topic (or the topic is not in the fanout),
+            fanout_size = 0
+            if topic in self.fanout:
+                fanout_size = len(self.fanout[topic])
+                # then it still adds them as above (if there are any)
+                for peer in self.fanout[topic]:
+                    self.mesh[topic].append(peer)
+                    await self.emit_graft(topic, peer)
+
+            if topic in self.peers_gossipsub:
+                # TODO: Should we have self.fanout[topic] here or [] (as the minus variable)?
+                # Selects the remaining number of peers (D-x) from peers.gossipsub[topic]
+                gossipsub_peers_in_topic = [peer for peer in self.pubsub.peer_topics[topic]
+                                            if peer in self.peers_gossipsub]
+                selected_peers = \
+                    GossipSub.select_from_minus(self.degree - fanout_size,
+                                                gossipsub_peers_in_topic,
+                                                self.fanout[topic] if topic in self.fanout else [])
+
+                # And likewise adds them to mesh[topic] and notifies them with a
+                # GRAFT(topic) control message.
+                for peer in selected_peers:
+                    self.mesh[topic].append(peer)
+                    await self.emit_graft(topic, peer)
+
+            # TODO: Do we remove all peers from fanout[topic]?
+
+    async def leave(self, topic):
+        # Note: the comments here are the near-exact algorithm description from the spec
+        """
+        Leave notifies the router that we are no longer interested in a topic.
+        It is invoked after the unsubscription announcement.
+        :param topic: topic to leave
+        """
+        # Notify the peers in mesh[topic] with a PRUNE(topic) message
+        for peer in self.mesh[topic]:
+            await self.emit_prune(topic, peer)
+
+        # Forget mesh[topic]
+        self.mesh.pop(topic, None)
+
+    # Interface Helper Functions
+    @staticmethod
+    def get_peer_type(protocol_id):
+        # TODO: Do this in a better, more efficient way
+        if "gossipsub" in protocol_id:
+            return "gossip"
+        if "floodsub" in protocol_id:
+            return "flood"
+        return "unknown"
+
+    async def deliver_messages_to_peers(self, peers, msg_sender, origin_id, serialized_packet):
+        for peer_id_in_topic in peers:
+            # Forward to all peers that are not the
+            # message sender and are not the message origin
+
+            if peer_id_in_topic not in (msg_sender, origin_id):
+                stream = self.pubsub.peers[peer_id_in_topic]
+
+                # Publish the packet
+                await stream.write(serialized_packet)
+
+    # Heartbeat
+    async def heartbeat(self):
+        """
+        Call individual heartbeats.
+        Note: the heartbeats are called with awaits because each heartbeat depends on the
+        state changes in the preceding heartbeat
+        """
+        while True:
+
+            await self.mesh_heartbeat()
+            await self.fanout_heartbeat()
+            await self.gossip_heartbeat()
+
+            await asyncio.sleep(self.heartbeat_interval)
+
+    async def mesh_heartbeat(self):
+        # Note: the comments here are the exact pseudocode from the spec
+        for topic in self.mesh:
+
+            num_mesh_peers_in_topic = len(self.mesh[topic])
+            if num_mesh_peers_in_topic < self.degree_low:
+
+                # Select D - |mesh[topic]| peers from peers.gossipsub[topic] - mesh[topic]
+                selected_peers = GossipSub.select_from_minus(self.degree - num_mesh_peers_in_topic,
+                                                             self.peers_gossipsub, self.mesh[topic])
+
+                for peer in selected_peers:
+                    # Add peer to mesh[topic]
+                    self.mesh[topic].append(peer)
+
+                    # Emit GRAFT(topic) control message to peer
+                    await self.emit_graft(topic, peer)
+
+            if num_mesh_peers_in_topic > self.degree_high:
+                # Select |mesh[topic]| - D peers from mesh[topic]
+                selected_peers = GossipSub.select_from_minus(num_mesh_peers_in_topic - self.degree,
+                                                             self.mesh[topic], [])
+                for peer in selected_peers:
+                    # Remove peer from mesh[topic]
+                    self.mesh[topic].remove(peer)
+
+                    # Emit PRUNE(topic) control message to peer
+                    await self.emit_prune(topic, peer)
+
+    async def fanout_heartbeat(self):
+        # Note: the comments here are the exact pseudocode from the spec
+        for topic in self.fanout:
+            # If time since last published > ttl
+            # TODO: there's no way time_since_last_publish gets set anywhere yet
+            if self.time_since_last_publish[topic] > self.time_to_live:
+                # Remove topic from fanout
+                self.fanout.remove(topic)
+                self.time_since_last_publish.remove(topic)
+            else:
+                num_fanout_peers_in_topic = len(self.fanout[topic])
+
+                # If |fanout[topic]| < D
+                if num_fanout_peers_in_topic < self.degree:
+                    # Select D - |fanout[topic]| peers from peers.gossipsub[topic] - fanout[topic]
+                    gossipsub_peers_in_topic = [peer for peer in self.pubsub.peer_topics[topic]
+                                                if peer in self.peers_gossipsub]
+                    selected_peers = \
+                        GossipSub.select_from_minus(self.degree - num_fanout_peers_in_topic,
+                                                    gossipsub_peers_in_topic, self.fanout[topic])
+
+                    # Add the peers to fanout[topic]
+                    self.fanout[topic].extend(selected_peers)
+
+    async def gossip_heartbeat(self):
+        # pylint: disable=too-many-nested-blocks
+        for topic in self.mesh:
+            msg_ids = self.mcache.window(topic)
+            if msg_ids:
+                # TODO: Make more efficient, possibly using a generator?
+                # Get all pubsub peers in a topic and only add them if they are gossipsub peers too
+                if topic in self.pubsub.peer_topics:
+                    gossipsub_peers_in_topic = [peer for peer in self.pubsub.peer_topics[topic]
+                                                if peer in self.peers_gossipsub]
+
+                    # Select D peers from peers.gossipsub[topic]
+                    peers_to_emit_ihave_to = \
+                        GossipSub.select_from_minus(self.degree, gossipsub_peers_in_topic, [])
+
+                    for peer in peers_to_emit_ihave_to:
+                        # TODO: this line is a monster, can hopefully be simplified
+                        if (topic not in self.mesh or (peer not in self.mesh[topic]))\
+                                and (topic not in self.fanout or (peer not in self.fanout[topic])):
+                            msg_ids = [str(msg) for msg in msg_ids]
+                            await self.emit_ihave(topic, msg_ids, peer)
+
+        # Do the same for fanout, for all topics not already hit in mesh
+        for topic in self.fanout:
+            if topic not in self.mesh:
+                msg_ids = self.mcache.window(topic)
+                if msg_ids:
+                    # TODO: Make more efficient, possibly using a generator?
+                    # Get all pubsub peers in topic and only add if they are gossipsub peers also
+                    if topic in self.pubsub.peer_topics:
+                        gossipsub_peers_in_topic = [peer for peer in self.pubsub.peer_topics[topic]
+                                                    if peer in self.peers_gossipsub]
+
+                        # Select D peers from peers.gossipsub[topic]
+                        peers_to_emit_ihave_to = \
+                            GossipSub.select_from_minus(self.degree, gossipsub_peers_in_topic, [])
+                        for peer in peers_to_emit_ihave_to:
+                            if peer not in self.mesh[topic] and peer not in self.fanout[topic]:
+
+                                msg_ids = [str(msg) for msg in msg_ids]
+                                await self.emit_ihave(topic, msg_ids, peer)
+
+        self.mcache.shift()
+
+    @staticmethod
+    def select_from_minus(num_to_select, pool, minus):
+        """
+        Select at most num_to_select subset of elements from the set (pool - minus) randomly.
+        :param num_to_select: number of elements to randomly select
+        :param pool: list of items to select from (excluding elements in minus)
+        :param minus: elements to be excluded from selection pool
+        :return: list of selected elements
+        """
+        # Create selection pool, which is selection_pool = pool - minus
+        if minus:
+            # Create a new selection pool by removing elements of minus
+            selection_pool = [x for x in pool if x not in minus]
+        else:
+            # Don't create a new selection_pool if we are not subbing anything
+            selection_pool = pool
+
+        # If num_to_select > size(selection_pool), then return selection_pool (which has the most
+        # possible elements s.t. the number of elements is less than num_to_select)
+        if num_to_select > len(selection_pool):
+            return selection_pool
+
+        # Random selection
+        selection = random.sample(selection_pool, num_to_select)
+
+        return selection
+
+    # RPC handlers
+
+    async def handle_ihave(self, ihave_msg, sender_peer_id):
+        """
+        Checks the seen set and requests unknown messages with an IWANT message.
+        """
+        # from_id_bytes = ihave_msg.from_id
+
+        from_id_str = sender_peer_id
+
+        # Get list of all seen (seqnos, from) from the (seqno, from) tuples in seen_messages cache
+        seen_seqnos_and_peers = [seqno_and_from
+                                 for seqno_and_from in self.pubsub.seen_messages.keys()]
+
+        # Add all unknown message ids (ids that appear in ihave_msg but not in seen_seqnos) to list
+        # of messages we want to request
+        msg_ids_wanted = [msg_id for msg_id in ihave_msg.messageIDs
+                          if literal_eval(msg_id) not in seen_seqnos_and_peers]
+
+        # Request messages with IWANT message
+        if msg_ids_wanted:
+            await self.emit_iwant(msg_ids_wanted, from_id_str)
+
+    async def handle_iwant(self, iwant_msg, sender_peer_id):
+        """
+        Forwards all request messages that are present in mcache to the requesting peer.
+        """
+        from_id_str = sender_peer_id
+
+        msg_ids = [literal_eval(msg) for msg in iwant_msg.messageIDs]
+        msgs_to_forward = []
+        for msg_id_iwant in msg_ids:
+            # Check if the wanted message ID is present in mcache
+            msg = self.mcache.get(msg_id_iwant)
+
+            # Cache hit
+            if msg:
+                # Add message to list of messages to forward to requesting peers
+                msgs_to_forward.append(msg)
+
+        # Forward messages to requesting peer
+        # Should this just be publishing? No
+        # because then the message will forwarded to peers in the topics contained in the messages.
+        # We should
+        # 1) Package these messages into a single packet
+        packet = rpc_pb2.RPC()
+
+        packet.publish.extend(msgs_to_forward)
+
+        # 2) Serialize that packet
+        rpc_msg = packet.SerializeToString()
+
+        # 3) Get the stream to this peer
+        # TODO: Should we pass in from_id or from_id_str here?
+        peer_stream = self.pubsub.peers[from_id_str]
+
+        # 4) And write the packet to the stream
+        await peer_stream.write(rpc_msg)
+
+    async def handle_graft(self, graft_msg, sender_peer_id):
+        topic = graft_msg.topicID
+
+        from_id_str = sender_peer_id
+
+        # Add peer to mesh for topic
+        if topic in self.mesh:
+            self.mesh[topic].append(from_id_str)
+        else:
+            self.mesh[topic] = [from_id_str]
+
+    async def handle_prune(self, prune_msg, sender_peer_id):
+        topic = prune_msg.topicID
+
+        from_id_str = sender_peer_id
+
+        # Remove peer from mesh for topic, if peer is in topic
+        if topic in self.mesh and from_id_str in self.mesh[topic]:
+            self.mesh[topic].remove(from_id_str)
+
+    # RPC emitters
+
+    async def emit_ihave(self, topic, msg_ids, to_peer):
+        """
+        Emit ihave message, sent to to_peer, for topic and msg_ids
+        """
+
+        ihave_msg = rpc_pb2.ControlIHave()
+        ihave_msg.messageIDs.extend(msg_ids)
+        ihave_msg.topicID = topic
+
+        control_msg = rpc_pb2.ControlMessage()
+        control_msg.ihave.extend([ihave_msg])
+
+        await self.emit_control_message(control_msg, to_peer)
+
+    async def emit_iwant(self, msg_ids, to_peer):
+        """
+        Emit iwant message, sent to to_peer, for msg_ids
+        """
+
+        iwant_msg = rpc_pb2.ControlIWant()
+        iwant_msg.messageIDs.extend(msg_ids)
+
+        control_msg = rpc_pb2.ControlMessage()
+        control_msg.iwant.extend([iwant_msg])
+
+        await self.emit_control_message(control_msg, to_peer)
+
+    async def emit_graft(self, topic, to_peer):
+        """
+        Emit graft message, sent to to_peer, for topic
+        """
+
+        graft_msg = rpc_pb2.ControlGraft()
+        graft_msg.topicID = topic
+
+        control_msg = rpc_pb2.ControlMessage()
+        control_msg.graft.extend([graft_msg])
+
+        await self.emit_control_message(control_msg, to_peer)
+
+    async def emit_prune(self, topic, to_peer):
+        """
+        Emit graft message, sent to to_peer, for topic
+        """
+
+        prune_msg = rpc_pb2.ControlPrune()
+        prune_msg.topicID = topic
+
+        control_msg = rpc_pb2.ControlMessage()
+        control_msg.prune.extend([prune_msg])
+
+        await self.emit_control_message(control_msg, to_peer)
+
+    async def emit_control_message(self, control_msg, to_peer):
+        # Add control message to packet
+        packet = rpc_pb2.RPC()
+        packet.control.CopyFrom(control_msg)
+
+        rpc_msg = packet.SerializeToString()
+
+        # Get stream for peer from pubsub
+        peer_stream = self.pubsub.peers[to_peer]
+
+        # Write rpc to stream
+        await peer_stream.write(rpc_msg)
diff --git a/libp2p/pubsub/mcache.py b/libp2p/pubsub/mcache.py
new file mode 100644
index 00000000..071945a5
--- /dev/null
+++ b/libp2p/pubsub/mcache.py
@@ -0,0 +1,92 @@
+class MessageCache:
+
+    class CacheEntry:
+        # pylint: disable=too-few-public-methods
+        """
+        A logical representation of an entry in the mcache's _history_.
+        """
+        def __init__(self, mid, topics):
+            """
+            Constructor.
+            :param mid: (seqno, from_id) of the msg
+            :param topics: list of topics this message was sent on
+            """
+            self.mid = mid
+            self.topics = topics
+
+    def __init__(self, window_size, history_size):
+        """
+        Constructor.
+        :param window_size: Size of the window desired.
+        :param history_size: Size of the history desired.
+        :return: the MessageCache
+        """
+        self.window_size = window_size
+        self.history_size = history_size
+
+        # (seqno, from_id) -> rpc message
+        self.msgs = dict()
+
+        # max length of history_size. each item is a list of CacheEntry.
+        # messages lost upon shift().
+        self.history = []
+
+        for _ in range(history_size):
+            self.history.append([])
+
+    def put(self, msg):
+        """
+        Put a message into the mcache.
+        :param msg: The rpc message to put in. Should contain seqno and from_id
+        """
+        mid = (msg.seqno, msg.from_id)
+        self.msgs[mid] = msg
+
+        if not self.history[0]:
+            self.history[0] = []
+
+        self.history[0].append(self.CacheEntry(mid, msg.topicIDs))
+
+    def get(self, mid):
+        """
+        Get a message from the mcache.
+        :param mid: (seqno, from_id) of the message to get.
+        :return: The rpc message associated with this mid
+        """
+        if mid in self.msgs:
+            return self.msgs[mid]
+
+        return None
+
+    def window(self, topic):
+        """
+        Get the window for this topic.
+        :param topic: Topic whose message ids we desire.
+        :return: List of mids in the current window.
+        """
+        mids = []
+
+        for entries_list in self.history[: self.window_size]:
+            for entry in entries_list:
+                for entry_topic in entry.topics:
+                    if entry_topic == topic:
+                        mids.append(entry.mid)
+
+        return mids
+
+    def shift(self):
+        """
+        Shift the window over by 1 position, dropping the last element of the history.
+        """
+        last_entries = self.history[len(self.history) - 1]
+
+        for entry in last_entries:
+            del self.msgs[entry.mid]
+
+        i = len(self.history) - 2
+
+        while i >= 0:
+            self.history[i + 1] = self.history[i]
+            i -= 1
+
+        self.history[0] = []
diff --git a/libp2p/pubsub/pubsub.py b/libp2p/pubsub/pubsub.py
index 2109a9ca..e0f6580f 100644
--- a/libp2p/pubsub/pubsub.py
+++ b/libp2p/pubsub/pubsub.py
@@ -1,5 +1,6 @@
 # pylint: disable=no-name-in-module
 import asyncio
+
 from lru import LRU
 
 from .pb import rpc_pb2
@@ -34,8 +35,7 @@ class Pubsub():
         for protocol in self.protocols:
             self.host.set_stream_handler(protocol, self.stream_handler)
 
-        # TODO: determine if these need to be asyncio queues, or if could possibly
-        # be ordinary blocking queues
+        # Use asyncio queues for proper context switching
         self.incoming_msgs_from_peers = asyncio.Queue()
         self.outgoing_messages = asyncio.Queue()
 
@@ -44,9 +44,10 @@ class Pubsub():
             self.cache_size = 128
         else:
             self.cache_size = cache_size
+
         self.seen_messages = LRU(self.cache_size)
 
-        # Map of topics we are subscribed to to handler functions
+        # Map of topics we are subscribed to blocking queues
         # for when the given topic receives a message
         self.my_topics = {}
 
@@ -96,6 +97,7 @@ class Pubsub():
                     if id_in_seen_msgs not in self.seen_messages:
                         should_publish = True
                         self.seen_messages[id_in_seen_msgs] = 1
+
                         await self.handle_talk(message)
 
             if rpc_incoming.subscriptions:
@@ -112,6 +114,10 @@ class Pubsub():
                 # relay message to peers with router
                 await self.router.publish(peer_id, incoming)
 
+            if rpc_incoming.control:
+                # Pass rpc to router so router could perform custom logic
+                await self.router.handle_rpc(rpc_incoming, peer_id)
+
             # Force context switch
             await asyncio.sleep(0)
 
@@ -180,8 +186,9 @@ class Pubsub():
                 # Add peer to topic
                 self.peer_topics[sub_message.topicid].append(origin_id)
         else:
-            # TODO: Remove peer from topic
-            pass
+            if sub_message.topicid in self.peer_topics:
+                if origin_id in self.peer_topics[sub_message.topicid]:
+                    self.peer_topics[sub_message.topicid].remove(origin_id)
 
     async def handle_talk(self, publish_message):
         """
@@ -217,7 +224,7 @@ class Pubsub():
         await self.message_all_peers(packet.SerializeToString())
 
         # Tell router we are joining this topic
-        self.router.join(topic_id)
+        await self.router.join(topic_id)
 
         # Return the asyncio queue for messages on this topic
         return self.my_topics[topic_id]
@@ -243,7 +250,7 @@ class Pubsub():
         await self.message_all_peers(packet.SerializeToString())
 
         # Tell router we are leaving this topic
-        self.router.leave(topic_id)
+        await self.router.leave(topic_id)
 
     async def message_all_peers(self, rpc_msg):
         """
diff --git a/libp2p/pubsub/pubsub_router_interface.py b/libp2p/pubsub/pubsub_router_interface.py
index ec5132e8..e581570c 100644
--- a/libp2p/pubsub/pubsub_router_interface.py
+++ b/libp2p/pubsub/pubsub_router_interface.py
@@ -31,10 +31,13 @@ class IPubsubRouter(ABC):
         """
 
     @abstractmethod
-    def handle_rpc(self, rpc):
+    def handle_rpc(self, rpc, sender_peer_id):
         """
         Invoked to process control messages in the RPC envelope.
         It is invoked after subscriptions and payload messages have been processed
+        TODO: Check if this interface is ok. It's not the exact same as the go code, but the go
+        code is really confusing with the msg origin, they specify `rpc.from` even when the rpc
+        shouldn't have a from
         :param rpc: rpc message
         """
 
diff --git a/setup.py b/setup.py
index 85420608..e244a8b3 100644
--- a/setup.py
+++ b/setup.py
@@ -25,7 +25,8 @@ setuptools.setup(
         "rpcudp",
         "grpcio",
         "grpcio-tools",
-        "lru-dict>=1.1.6"
+        "lru-dict>=1.1.6",
+        "aio_timers"
     ],
     packages=["libp2p"],
     zip_safe=False,
diff --git a/tests/pubsub/test_floodsub.py b/tests/pubsub/test_floodsub.py
index 06c1cbd4..2c67185c 100644
--- a/tests/pubsub/test_floodsub.py
+++ b/tests/pubsub/test_floodsub.py
@@ -613,4 +613,4 @@ async def test_five_nodes_ring_two_topic_diff_origin_many_msgs_test_obj():
             }
         ]
     }
-    await perform_test_from_obj(test_obj)
\ No newline at end of file
+    await perform_test_from_obj(test_obj)
diff --git a/tests/pubsub/test_gossipsub.py b/tests/pubsub/test_gossipsub.py
new file mode 100644
index 00000000..0c94faee
--- /dev/null
+++ b/tests/pubsub/test_gossipsub.py
@@ -0,0 +1,271 @@
+import asyncio
+import pytest
+import random
+
+from libp2p.pubsub.gossipsub import GossipSub
+from libp2p.pubsub.floodsub import FloodSub
+from libp2p.pubsub.pb import rpc_pb2
+from libp2p.pubsub.pubsub import Pubsub
+from utils import message_id_generator, generate_RPC_packet, \
+    create_libp2p_hosts, create_pubsub_and_gossipsub_instances, sparse_connect, dense_connect, \
+    connect
+from tests.utils import cleanup
+
+SUPPORTED_PROTOCOLS = ["/gossipsub/1.0.0"]
+
+
+@pytest.mark.asyncio
+async def test_dense():
+    # Create libp2p hosts
+    next_msg_id_func = message_id_generator(0)
+
+    num_hosts = 10
+    num_msgs = 5
+    libp2p_hosts = await create_libp2p_hosts(num_hosts)
+
+    # Create pubsub, gossipsub instances
+    pubsubs, gossipsubs = create_pubsub_and_gossipsub_instances(libp2p_hosts, \
+                                                                SUPPORTED_PROTOCOLS, \
+                                                                10, 9, 11, 30, 3, 5, 0.5)
+
+    # All pubsub subscribe to foobar
+    queues = []
+    for pubsub in pubsubs:
+        q = await pubsub.subscribe("foobar")
+
+        # Add each blocking queue to an array of blocking queues
+        queues.append(q)
+
+    # Sparsely connect libp2p hosts in random way
+    await dense_connect(libp2p_hosts)
+
+    # Wait 2 seconds for heartbeat to allow mesh to connect
+    await asyncio.sleep(2)
+
+    for i in range(num_msgs):
+        msg_content = "foo " + str(i)
+
+        # randomly pick a message origin
+        origin_idx = random.randint(0, num_hosts - 1)
+        origin_host = libp2p_hosts[origin_idx]
+        host_id = str(origin_host.get_id())
+
+        # Generate message packet
+        packet = generate_RPC_packet(host_id, ["foobar"], msg_content, next_msg_id_func())
+
+        # publish from the randomly chosen host
+        await gossipsubs[origin_idx].publish(host_id, packet.SerializeToString())
+
+        await asyncio.sleep(0.5)
+        # Assert that all blocking queues receive the message
+        items = []
+        for queue in queues:
+            msg = await queue.get()
+            assert msg.data == packet.publish[0].data
+            items.append(msg.data)
+    await cleanup()
+
+@pytest.mark.asyncio
+async def test_fanout():
+    # Create libp2p hosts
+    next_msg_id_func = message_id_generator(0)
+
+    num_hosts = 10
+    num_msgs = 5
+    libp2p_hosts = await create_libp2p_hosts(num_hosts)
+
+    # Create pubsub, gossipsub instances
+    pubsubs, gossipsubs = create_pubsub_and_gossipsub_instances(libp2p_hosts, \
+                                                                SUPPORTED_PROTOCOLS, \
+                                                                10, 9, 11, 30, 3, 5, 0.5)
+
+    # All pubsub subscribe to foobar
+    queues = []
+    for i in range(1, len(pubsubs)):
+        q = await pubsubs[i].subscribe("foobar")
+
+        # Add each blocking queue to an array of blocking queues
+        queues.append(q)
+
+    # Sparsely connect libp2p hosts in random way
+    await dense_connect(libp2p_hosts)
+
+    # Wait 2 seconds for heartbeat to allow mesh to connect
+    await asyncio.sleep(2)
+
+    # Send messages with origin not subscribed
+    for i in range(num_msgs):
+        msg_content = "foo " + str(i)
+
+        # Pick the message origin to the node that is not subscribed to 'foobar'
+        origin_idx = 0
+        origin_host = libp2p_hosts[origin_idx]
+        host_id = str(origin_host.get_id())
+
+        # Generate message packet
+        packet = generate_RPC_packet(host_id, ["foobar"], msg_content, next_msg_id_func())
+
+        # publish from the randomly chosen host
+        await gossipsubs[origin_idx].publish(host_id, packet.SerializeToString())
+
+        await asyncio.sleep(0.5)
+        # Assert that all blocking queues receive the message
+        for queue in queues:
+            msg = await queue.get()
+            assert msg.SerializeToString() == packet.publish[0].SerializeToString()
+
+    # Subscribe message origin
+    queues.append(await pubsubs[0].subscribe("foobar"))
+
+    # Send messages again
+    for i in range(num_msgs):
+        msg_content = "foo " + str(i)
+
+        # Pick the message origin to the node that is not subscribed to 'foobar'
+        origin_idx = 0
+        origin_host = libp2p_hosts[origin_idx]
+        host_id = str(origin_host.get_id())
+
+        # Generate message packet
+        packet = generate_RPC_packet(host_id, ["foobar"], msg_content, next_msg_id_func())
+
+        # publish from the randomly chosen host
+        await gossipsubs[origin_idx].publish(host_id, packet.SerializeToString())
+
+        await asyncio.sleep(0.5)
+        # Assert that all blocking queues receive the message
+        for queue in queues:
+            msg = await queue.get()
+            assert msg.SerializeToString() == packet.publish[0].SerializeToString()
+
+    await cleanup()
+
+@pytest.mark.asyncio
+async def test_fanout_maintenance():
+    # Create libp2p hosts
+    next_msg_id_func = message_id_generator(0)
+
+    num_hosts = 10
+    num_msgs = 5
+    libp2p_hosts = await create_libp2p_hosts(num_hosts)
+
+    # Create pubsub, gossipsub instances
+    pubsubs, gossipsubs = create_pubsub_and_gossipsub_instances(libp2p_hosts, \
+                                                                SUPPORTED_PROTOCOLS, \
+                                                                10, 9, 11, 30, 3, 5, 0.5)
+
+    # All pubsub subscribe to foobar
+    queues = []
+    for i in range(1, len(pubsubs)):
+        q = await pubsubs[i].subscribe("foobar")
+
+        # Add each blocking queue to an array of blocking queues
+        queues.append(q)
+
+    # Sparsely connect libp2p hosts in random way
+    await dense_connect(libp2p_hosts)
+
+    # Wait 2 seconds for heartbeat to allow mesh to connect
+    await asyncio.sleep(2)
+
+    # Send messages with origin not subscribed
+    for i in range(num_msgs):
+        msg_content = "foo " + str(i)
+
+        # Pick the message origin to the node that is not subscribed to 'foobar'
+        origin_idx = 0
+        origin_host = libp2p_hosts[origin_idx]
+        host_id = str(origin_host.get_id())
+
+        # Generate message packet
+        packet = generate_RPC_packet(host_id, ["foobar"], msg_content, next_msg_id_func())
+
+        # publish from the randomly chosen host
+        await gossipsubs[origin_idx].publish(host_id, packet.SerializeToString())
+
+        await asyncio.sleep(0.5)
+        # Assert that all blocking queues receive the message
+        for queue in queues:
+            msg = await queue.get()
+            assert msg.SerializeToString() == packet.publish[0].SerializeToString()
+
+    for sub in pubsubs:
+        await sub.unsubscribe('foobar')
+
+    queues = []
+
+    await asyncio.sleep(2)
+
+    # Resub and repeat
+    for i in range(1, len(pubsubs)):
+        q = await pubsubs[i].subscribe("foobar")
+
+        # Add each blocking queue to an array of blocking queues
+        queues.append(q)
+
+    await asyncio.sleep(2)
+
+    # Check messages can still be sent
+    for i in range(num_msgs):
+        msg_content = "foo " + str(i)
+
+        # Pick the message origin to the node that is not subscribed to 'foobar'
+        origin_idx = 0
+        origin_host = libp2p_hosts[origin_idx]
+        host_id = str(origin_host.get_id())
+
+        # Generate message packet
+        packet = generate_RPC_packet(host_id, ["foobar"], msg_content, next_msg_id_func())
+
+        # publish from the randomly chosen host
+        await gossipsubs[origin_idx].publish(host_id, packet.SerializeToString())
+
+        await asyncio.sleep(0.5)
+        # Assert that all blocking queues receive the message
+        for queue in queues:
+            msg = await queue.get()
+            assert msg.SerializeToString() == packet.publish[0].SerializeToString()
+
+    await cleanup()
+
+@pytest.mark.asyncio
+async def test_gossip_propagation():
+    # Create libp2p hosts
+    next_msg_id_func = message_id_generator(0)
+
+    num_hosts = 2
+    libp2p_hosts = await create_libp2p_hosts(num_hosts)
+
+    # Create pubsub, gossipsub instances
+    pubsubs, gossipsubs = create_pubsub_and_gossipsub_instances(libp2p_hosts, \
+                                                                SUPPORTED_PROTOCOLS, \
+                                                                1, 0, 2, 30, 50, 100, 0.5)
+    node1, node2 = libp2p_hosts[0], libp2p_hosts[1]
+    sub1, sub2 = pubsubs[0], pubsubs[1]
+    gsub1, gsub2 = gossipsubs[0], gossipsubs[1]
+
+    node1_queue = await sub1.subscribe('foo')
+
+    # node 1 publish to topic
+    msg_content = 'foo_msg'
+    node1_id = str(node1.get_id())
+
+    # Generate message packet
+    packet = generate_RPC_packet(node1_id, ["foo"], msg_content, next_msg_id_func())
+
+    # publish from the randomly chosen host
+    await gsub1.publish(node1_id, packet.SerializeToString())
+
+    # now node 2 subscribes
+    node2_queue = await sub2.subscribe('foo')
+
+    await connect(node2, node1)
+
+    # wait for gossip heartbeat
+    await asyncio.sleep(2)
+
+    # should be able to read message
+    msg = await node2_queue.get()
+    assert msg.SerializeToString() == packet.publish[0].SerializeToString()
+
+    await cleanup()
diff --git a/tests/pubsub/test_gossipsub_backward_compatibility.py b/tests/pubsub/test_gossipsub_backward_compatibility.py
new file mode 100644
index 00000000..468e25fd
--- /dev/null
+++ b/tests/pubsub/test_gossipsub_backward_compatibility.py
@@ -0,0 +1,519 @@
+import asyncio
+import multiaddr
+import pytest
+
+from libp2p import new_node
+from libp2p.peer.peerinfo import info_from_p2p_addr
+from libp2p.pubsub.gossipsub import GossipSub
+from libp2p.pubsub.floodsub import FloodSub
+from libp2p.pubsub.pb import rpc_pb2
+from libp2p.pubsub.pubsub import Pubsub
+from utils import message_id_generator, generate_RPC_packet
+from tests.utils import cleanup
+
+# pylint: disable=too-many-locals
+
+async def connect(node1, node2):
+    """
+    Connect node1 to node2
+    """
+    addr = node2.get_addrs()[0]
+    info = info_from_p2p_addr(addr)
+    await node1.connect(info)
+
+@pytest.mark.asyncio
+async def test_init():
+    node = await new_node(transport_opt=["/ip4/127.1/tcp/0"])
+
+    await node.get_network().listen(multiaddr.Multiaddr("/ip4/127.1/tcp/0"))
+
+    supported_protocols = ["/gossipsub/1.0.0"]
+
+    gossipsub = GossipSub(supported_protocols, 3, 2, 4, 30)
+    pubsub = Pubsub(node, gossipsub, "a")
+
+    # Did it work?
+    assert gossipsub and pubsub
+
+    await cleanup()
+
+async def perform_test_from_obj(obj):
+    """
+    Perform a floodsub test from a test obj.
+    test obj are composed as follows:
+    
+    {
+        "supported_protocols": ["supported/protocol/1.0.0",...],
+        "adj_list": {
+            "node1": ["neighbor1_of_node1", "neighbor2_of_node1", ...],
+            "node2": ["neighbor1_of_node2", "neighbor2_of_node2", ...],
+            ...
+        },
+        "topic_map": {
+            "topic1": ["node1_subscribed_to_topic1", "node2_subscribed_to_topic1", ...]
+        },
+        "messages": [
+            {
+                "topics": ["topic1_for_message", "topic2_for_message", ...],
+                "data": "some contents of the message (newlines are not supported)",
+                "node_id": "message sender node id"
+            },
+            ...
+        ]
+    }
+    NOTE: In adj_list, for any neighbors A and B, only list B as a neighbor of A
+    or B as a neighbor of A once. Do NOT list both A: ["B"] and B:["A"] as the behavior
+    is undefined (even if it may work)
+    """
+
+    # Step 1) Create graph
+    adj_list = obj["adj_list"]
+    node_map = {}
+    gossipsub_map = {}
+    pubsub_map = {}
+
+    supported_protocols = obj["supported_protocols"]
+
+    tasks_connect = []
+    for start_node_id in adj_list:
+        # Create node if node does not yet exist
+        if start_node_id not in node_map:
+            node = await new_node(transport_opt=["/ip4/127.0.0.1/tcp/0"])
+            await node.get_network().listen(multiaddr.Multiaddr("/ip4/127.0.0.1/tcp/0"))
+
+            node_map[start_node_id] = node
+
+            gossipsub = GossipSub(supported_protocols, 3, 2, 4, 30)
+            gossipsub_map[start_node_id] = gossipsub
+            pubsub = Pubsub(node, gossipsub, start_node_id)
+            pubsub_map[start_node_id] = pubsub
+
+        # For each neighbor of start_node, create if does not yet exist,
+        # then connect start_node to neighbor
+        for neighbor_id in adj_list[start_node_id]:
+            # Create neighbor if neighbor does not yet exist
+            if neighbor_id not in node_map:
+                neighbor_node = await new_node(transport_opt=["/ip4/127.0.0.1/tcp/0"])
+                await neighbor_node.get_network().listen(multiaddr.Multiaddr("/ip4/127.0.0.1/tcp/0"))
+                
+                node_map[neighbor_id] = neighbor_node
+
+                gossipsub = GossipSub(supported_protocols, 3, 2, 4, 30)
+                gossipsub_map[neighbor_id] = gossipsub
+                pubsub = Pubsub(neighbor_node, gossipsub, neighbor_id)
+                pubsub_map[neighbor_id] = pubsub
+
+            # Connect node and neighbor
+            tasks_connect.append(asyncio.ensure_future(connect(node_map[start_node_id], node_map[neighbor_id])))
+    tasks_connect.append(asyncio.sleep(2))
+    await asyncio.gather(*tasks_connect)
+
+    # Allow time for graph creation before continuing
+    # await asyncio.sleep(0.25)
+
+    # Step 2) Subscribe to topics
+    queues_map = {}
+    topic_map = obj["topic_map"]
+
+    tasks_topic = []
+    tasks_topic_data = []
+    for topic in topic_map:
+        for node_id in topic_map[topic]:
+            """
+            # Subscribe node to topic
+            q = await pubsub_map[node_id].subscribe(topic)
+
+            # Create topic-queue map for node_id if one does not yet exist
+            if node_id not in queues_map:
+                queues_map[node_id] = {}
+
+            # Store queue in topic-queue map for node
+            queues_map[node_id][topic] = q
+            """
+            tasks_topic.append(asyncio.ensure_future(pubsub_map[node_id].subscribe(topic)))
+            tasks_topic_data.append((node_id, topic))
+    tasks_topic.append(asyncio.sleep(2))
+
+    # Gather is like Promise.all
+    responses = await asyncio.gather(*tasks_topic, return_exceptions=True)
+    for i in range(len(responses) - 1):
+        q = responses[i]
+        node_id, topic = tasks_topic_data[i]
+        if node_id not in queues_map:
+            queues_map[node_id] = {}
+
+        # Store queue in topic-queue map for node
+        queues_map[node_id][topic] = q
+
+    # Allow time for subscribing before continuing
+    # await asyncio.sleep(0.01)
+
+    # Step 3) Publish messages
+    topics_in_msgs_ordered = []
+    messages = obj["messages"]
+    tasks_publish = []
+    next_msg_id_func = message_id_generator(0)
+
+    for msg in messages:
+        topics = msg["topics"]
+
+        data = msg["data"]
+        node_id = msg["node_id"]
+
+        # Get actual id for sender node (not the id from the test obj)
+        actual_node_id = str(node_map[node_id].get_id())
+
+        # Create correctly formatted message
+        msg_talk = generate_RPC_packet(actual_node_id, topics, data, next_msg_id_func())
+
+        # Publish message
+        tasks_publish.append(asyncio.ensure_future(gossipsub_map[node_id].publish(\
+            actual_node_id, msg_talk.SerializeToString())))
+
+        # For each topic in topics, add topic, msg_talk tuple to ordered test list
+        # TODO: Update message sender to be correct message sender before
+        # adding msg_talk to this list
+        for topic in topics:
+            topics_in_msgs_ordered.append((topic, msg_talk))
+
+    # Allow time for publishing before continuing
+    # await asyncio.sleep(0.4)
+    tasks_publish.append(asyncio.sleep(2))
+    await asyncio.gather(*tasks_publish)
+
+    # Step 4) Check that all messages were received correctly.
+    # TODO: Check message sender too
+    for i in range(len(topics_in_msgs_ordered)):
+        topic, actual_msg = topics_in_msgs_ordered[i]
+
+        # Look at each node in each topic
+        for node_id in topic_map[topic]:
+            # Get message from subscription queue
+            msg_on_node = await queues_map[node_id][topic].get()
+            assert actual_msg.publish[0].SerializeToString() == msg_on_node.SerializeToString()
+
+    # Success, terminate pending tasks.
+    await cleanup()
+
+@pytest.mark.asyncio
+async def test_simple_two_nodes_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "A": ["B"]
+        },
+        "topic_map": {
+            "topic1": ["B"]
+        },
+        "messages": [
+            {
+                "topics": ["topic1"],
+                "data": "foo",
+                "node_id": "A"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_three_nodes_two_topics_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "A": ["B"],
+            "B": ["C"]
+        },
+        "topic_map": {
+            "topic1": ["B", "C"],
+            "topic2": ["B", "C"]
+        },
+        "messages": [
+            {
+                "topics": ["topic1"],
+                "data": "foo",
+                "node_id": "A"
+            },
+            {
+                "topics": ["topic2"],
+                "data": "Alex is tall",
+                "node_id": "A"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_two_nodes_one_topic_single_subscriber_is_sender_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "A": ["B"]
+        },
+        "topic_map": {
+            "topic1": ["B"]
+        },
+        "messages": [
+            {
+                "topics": ["topic1"],
+                "data": "Alex is tall",
+                "node_id": "B"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_two_nodes_one_topic_two_msgs_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "A": ["B"]
+        },
+        "topic_map": {
+            "topic1": ["B"]
+        },
+        "messages": [
+            {
+                "topics": ["topic1"],
+                "data": "Alex is tall",
+                "node_id": "B"
+            },
+            {
+                "topics": ["topic1"],
+                "data": "foo",
+                "node_id": "A"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_seven_nodes_tree_one_topics_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "1": ["2", "3"],
+            "2": ["4", "5"],
+            "3": ["6", "7"]
+        },
+        "topic_map": {
+            "astrophysics": ["2", "3", "4", "5", "6", "7"]
+        },
+        "messages": [
+            {
+                "topics": ["astrophysics"],
+                "data": "e=mc^2",
+                "node_id": "1"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_seven_nodes_tree_three_topics_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "1": ["2", "3"],
+            "2": ["4", "5"],
+            "3": ["6", "7"]
+        },
+        "topic_map": {
+            "astrophysics": ["2", "3", "4", "5", "6", "7"],
+            "space": ["2", "3", "4", "5", "6", "7"],
+            "onions": ["2", "3", "4", "5", "6", "7"]
+        },
+        "messages": [
+            {
+                "topics": ["astrophysics"],
+                "data": "e=mc^2",
+                "node_id": "1"
+            },
+            {
+                "topics": ["space"],
+                "data": "foobar",
+                "node_id": "1"
+            },
+            {
+                "topics": ["onions"],
+                "data": "I am allergic",
+                "node_id": "1"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_seven_nodes_tree_three_topics_diff_origin_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "1": ["2", "3"],
+            "2": ["4", "5"],
+            "3": ["6", "7"]
+        },
+        "topic_map": {
+            "astrophysics": ["1", "2", "3", "4", "5", "6", "7"],
+            "space": ["1", "2", "3", "4", "5", "6", "7"],
+            "onions": ["1", "2", "3", "4", "5", "6", "7"]
+        },
+        "messages": [
+            {
+                "topics": ["astrophysics"],
+                "data": "e=mc^2",
+                "node_id": "1"
+            },
+            {
+                "topics": ["space"],
+                "data": "foobar",
+                "node_id": "4"
+            },
+            {
+                "topics": ["onions"],
+                "data": "I am allergic",
+                "node_id": "7"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_three_nodes_clique_two_topic_diff_origin_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "1": ["2", "3"],
+            "2": ["3"]
+        },
+        "topic_map": {
+            "astrophysics": ["1", "2", "3"],
+            "school": ["1", "2", "3"]
+        },
+        "messages": [
+            {
+                "topics": ["astrophysics"],
+                "data": "e=mc^2",
+                "node_id": "1"
+            },
+            {
+                "topics": ["school"],
+                "data": "foobar",
+                "node_id": "2"
+            },
+            {
+                "topics": ["astrophysics"],
+                "data": "I am allergic",
+                "node_id": "1"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_four_nodes_clique_two_topic_diff_origin_many_msgs_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "1": ["2", "3", "4"],
+            "2": ["1", "3", "4"],
+            "3": ["1", "2", "4"],
+            "4": ["1", "2", "3"]
+        },
+        "topic_map": {
+            "astrophysics": ["1", "2", "3", "4"],
+            "school": ["1", "2", "3", "4"]
+        },
+        "messages": [
+            {
+                "topics": ["astrophysics"],
+                "data": "e=mc^2",
+                "node_id": "1"
+            },
+            {
+                "topics": ["school"],
+                "data": "foobar",
+                "node_id": "2"
+            },
+            {
+                "topics": ["astrophysics"],
+                "data": "I am allergic",
+                "node_id": "1"
+            },
+            {
+                "topics": ["school"],
+                "data": "foobar2",
+                "node_id": "2"
+            },
+            {
+                "topics": ["astrophysics"],
+                "data": "I am allergic2",
+                "node_id": "1"
+            },
+            {
+                "topics": ["school"],
+                "data": "foobar3",
+                "node_id": "2"
+            },
+            {
+                "topics": ["astrophysics"],
+                "data": "I am allergic3",
+                "node_id": "1"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
+
+@pytest.mark.asyncio
+async def test_five_nodes_ring_two_topic_diff_origin_many_msgs_test_obj():
+    test_obj = {
+        "supported_protocols": ["/floodsub/1.0.0"],
+        "adj_list": {
+            "1": ["2"],
+            "2": ["3"],
+            "3": ["4"],
+            "4": ["5"],
+            "5": ["1"]
+        },
+        "topic_map": {
+            "astrophysics": ["1", "2", "3", "4", "5"],
+            "school": ["1", "2", "3", "4", "5"]
+        },
+        "messages": [
+            {
+                "topics": ["astrophysics"],
+                "data": "e=mc^2",
+                "node_id": "1"
+            },
+            {
+                "topics": ["school"],
+                "data": "foobar",
+                "node_id": "2"
+            },
+            {
+                "topics": ["astrophysics"],
+                "data": "I am allergic",
+                "node_id": "1"
+            },
+            {
+                "topics": ["school"],
+                "data": "foobar2",
+                "node_id": "2"
+            },
+            {
+                "topics": ["astrophysics"],
+                "data": "I am allergic2",
+                "node_id": "1"
+            },
+            {
+                "topics": ["school"],
+                "data": "foobar3",
+                "node_id": "2"
+            },
+            {
+                "topics": ["astrophysics"],
+                "data": "I am allergic3",
+                "node_id": "1"
+            }
+        ]
+    }
+    await perform_test_from_obj(test_obj)
diff --git a/tests/pubsub/test_mcache.py b/tests/pubsub/test_mcache.py
new file mode 100644
index 00000000..5446f74c
--- /dev/null
+++ b/tests/pubsub/test_mcache.py
@@ -0,0 +1,129 @@
+import pytest
+from libp2p.pubsub.mcache import MessageCache
+
+
+class Msg:
+
+    def __init__(self, topicIDs, seqno, from_id):
+        self.topicIDs = topicIDs
+        self.seqno = seqno,
+        self.from_id = from_id
+
+@pytest.mark.asyncio
+async def test_mcache():
+    # Ported from:
+    # https://github.com/libp2p/go-libp2p-pubsub
+    # /blob/51b7501433411b5096cac2b4994a36a68515fc03/mcache_test.go
+    mcache = MessageCache(3, 5)
+    msgs = []
+
+    for i in range(60):
+        msgs.append(Msg(["test"], i, "test"))
+
+    for i in range(10):
+        mcache.put(msgs[i])
+
+    for i in range(10):
+        msg = msgs[i]
+        mid = (msg.seqno, msg.from_id)
+        get_msg = mcache.get(mid)
+
+        # successful read
+        assert get_msg == msg
+
+    gids = mcache.window('test')
+
+    assert len(gids) == 10
+
+    for i in range(10):
+        msg = msgs[i]
+        mid = (msg.seqno, msg.from_id)
+
+        assert mid == gids[i]
+
+    mcache.shift()
+
+    for i in range(10, 20):
+        mcache.put(msgs[i])
+
+    for i in range(20):
+        msg = msgs[i]
+        mid = (msg.seqno, msg.from_id)
+        get_msg = mcache.get(mid)
+
+        assert get_msg == msg
+
+    gids = mcache.window('test')
+
+    assert len(gids) == 20
+
+    for i in range(10):
+        msg = msgs[i]
+        mid = (msg.seqno, msg.from_id)
+
+        assert mid == gids[10 + i]
+
+    for i in range(10, 20):
+        msg = msgs[i]
+        mid = (msg.seqno, msg.from_id)
+
+        assert mid == gids[i - 10]
+
+    mcache.shift()
+
+    for i in range(20, 30):
+        mcache.put(msgs[i])
+
+    mcache.shift()
+
+    for i in range(30, 40):
+        mcache.put(msgs[i])
+
+    mcache.shift()
+
+    for i in range(40, 50):
+        mcache.put(msgs[i])
+
+    mcache.shift()
+
+    for i in range(50, 60):
+        mcache.put(msgs[i])
+
+    assert len(mcache.msgs) == 50
+
+    for i in range(10):
+        msg = msgs[i]
+        mid = (msg.seqno, msg.from_id)
+        get_msg = mcache.get(mid)
+
+        # Should be evicted from cache
+        assert not get_msg
+
+    for i in range(10, 60):
+        msg = msgs[i]
+        mid = (msg.seqno, msg.from_id)
+        get_msg = mcache.get(mid)
+
+        assert get_msg == msg
+
+    gids = mcache.window('test')
+
+    assert len(gids) == 30
+
+    for i in range(10):
+        msg = msgs[50 + i]
+        mid = (msg.seqno, msg.from_id)
+
+        assert mid == gids[i]
+
+    for i in range(10, 20):
+        msg = msgs[30 + i]
+        mid = (msg.seqno, msg.from_id)
+
+        assert mid == gids[i]
+
+    for i in range(20, 30):
+        msg = msgs[10 + i]
+        mid = (msg.seqno, msg.from_id)
+
+        assert mid == gids[i]
diff --git a/tests/pubsub/utils.py b/tests/pubsub/utils.py
index 056baac0..66916613 100644
--- a/tests/pubsub/utils.py
+++ b/tests/pubsub/utils.py
@@ -1,6 +1,13 @@
+import asyncio
+import multiaddr
 import uuid
+import random
 import struct
+from libp2p import new_node
 from libp2p.pubsub.pb import rpc_pb2
+from libp2p.peer.peerinfo import info_from_p2p_addr
+from libp2p.pubsub.pubsub import Pubsub
+from libp2p.pubsub.gossipsub import GossipSub
 
 
 def message_id_generator(start_val):
@@ -42,3 +49,76 @@ def generate_RPC_packet(origin_id, topics, msg_content, msg_id):
 
     packet.publish.extend([message])
     return packet
+
+async def connect(node1, node2):
+    """
+    Connect node1 to node2
+    """
+    addr = node2.get_addrs()[0]
+    info = info_from_p2p_addr(addr)
+    await node1.connect(info)
+
+async def create_libp2p_hosts(num_hosts):
+    """
+    Create libp2p hosts
+    :param num_hosts: number of hosts to create
+    """
+    hosts = []
+    tasks_create = []
+    for i in range(0, num_hosts):
+        # Create node
+        tasks_create.append(asyncio.ensure_future(new_node(transport_opt=["/ip4/127.0.0.1/tcp/0"])))
+    hosts = await asyncio.gather(*tasks_create)
+
+    tasks_listen = []
+    for node in hosts:
+        # Start listener
+        tasks_listen.append(asyncio.ensure_future(node.get_network().listen(multiaddr.Multiaddr("/ip4/127.0.0.1/tcp/0"))))
+    await asyncio.gather(*tasks_listen)
+
+    return hosts
+
+def create_pubsub_and_gossipsub_instances(libp2p_hosts, supported_protocols, degree, degree_low, \
+    degree_high, time_to_live, gossip_window, gossip_history, heartbeat_interval):
+    pubsubs = []
+    gossipsubs = []
+    for node in libp2p_hosts:
+        gossipsub = GossipSub(supported_protocols, degree,
+                              degree_low, degree_high, time_to_live,
+                              gossip_window, gossip_history,
+                              heartbeat_interval)
+        pubsub = Pubsub(node, gossipsub, "a")
+        pubsubs.append(pubsub)
+        gossipsubs.append(gossipsub)
+
+    return pubsubs, gossipsubs
+
+async def sparse_connect(hosts):
+    await connect_some(hosts, 3)
+
+
+async def dense_connect(hosts):
+    await connect_some(hosts, 10)
+
+
+async def connect_some(hosts, degree):
+    for i, host in enumerate(hosts):
+        for j, host2 in enumerate(hosts):
+            if i != j and i < j:
+                await connect(host, host2)
+
+    # TODO: USE THE CODE BELOW
+    # for i, host in enumerate(hosts):
+    #     j = 0
+    #     while j < degree:
+    #         n = random.randint(0, len(hosts) - 1)
+
+    #         if n == i:
+    #             j -= 1
+    #             continue
+
+    #         neighbor = hosts[n]
+
+    #         await connect(host, neighbor)
+
+    #         j += 1