diff --git a/beacon_node/client/src/lib.rs b/beacon_node/client/src/lib.rs
index 44eab4fe2..b24d2cb7f 100644
--- a/beacon_node/client/src/lib.rs
+++ b/beacon_node/client/src/lib.rs
@@ -46,7 +46,7 @@ impl<TClientType: ClientTypes> Client<TClientType> {
         // TODO: Add beacon_chain reference to network parameters
         let network_config = &config.net_conf;
         let network_logger = log.new(o!("Service" => "Network"));
-        let (network, _network_send) = NetworkService::new(
+        let (network, network_send) = NetworkService::new(
             beacon_chain.clone(),
             network_config,
             executor,
@@ -59,6 +59,7 @@ impl<TClientType: ClientTypes> Client<TClientType> {
             rpc_exit_signal = Some(rpc::start_server(
                 &config.rpc_conf,
                 executor,
+                network_send,
                 beacon_chain.clone(),
                 &log,
             ));
diff --git a/beacon_node/eth2-libp2p/src/behaviour.rs b/beacon_node/eth2-libp2p/src/behaviour.rs
index 3d5b94353..b3c4213b1 100644
--- a/beacon_node/eth2-libp2p/src/behaviour.rs
+++ b/beacon_node/eth2-libp2p/src/behaviour.rs
@@ -14,6 +14,7 @@ use libp2p::{
     NetworkBehaviour, PeerId,
 };
 use slog::{debug, o};
+use ssz::{ssz_encode, Decodable, DecodeError, Encodable, SszStream};
 use ssz_derive::{Decode, Encode};
 use types::Attestation;
 use types::Topic;
@@ -124,6 +125,15 @@ impl<TSubstream: AsyncRead + AsyncWrite> Behaviour<TSubstream> {
         }
     }
 
+    /* Behaviour functions */
+
+    /// Publishes a message on the pubsub (gossipsub) behaviour.
+    pub fn publish(&mut self, topic: Topic, message: PubsubMessage) {
+        //encode the message
+        let message_bytes = ssz_encode(&message);
+        self.gossipsub.publish(topic, message_bytes);
+    }
+
     /// Consumes the events list when polled.
     fn poll<TBehaviourIn>(
         &mut self,
@@ -158,12 +168,6 @@ pub enum BehaviourEvent {
     Message(String),
 }
 
-#[derive(Debug, Clone)]
-pub enum IncomingGossip {
-    Block(BlockGossip),
-    Attestation(AttestationGossip),
-}
-
 /// Gossipsub message providing notification of a new block.
 #[derive(Encode, Decode, Clone, Debug, PartialEq)]
 pub struct BlockGossip {
@@ -175,3 +179,43 @@ pub struct BlockGossip {
 pub struct AttestationGossip {
     pub attestation: Attestation,
 }
+
+/// Messages that are passed to and from the pubsub (Gossipsub) behaviour.
+#[derive(Debug, Clone)]
+pub enum PubsubMessage {
+    Block(BlockGossip),
+    Attestation(AttestationGossip),
+}
+
+//TODO: Correctly encode/decode enums. Prefixing with integer for now.
+impl Encodable for PubsubMessage {
+    fn ssz_append(&self, s: &mut SszStream) {
+        match self {
+            PubsubMessage::Block(block_gossip) => {
+                0u32.ssz_append(s);
+                block_gossip.ssz_append(s);
+            }
+            PubsubMessage::Attestation(attestation_gossip) => {
+                1u32.ssz_append(s);
+                attestation_gossip.ssz_append(s);
+            }
+        }
+    }
+}
+
+impl Decodable for PubsubMessage {
+    fn ssz_decode(bytes: &[u8], index: usize) -> Result<(Self, usize), DecodeError> {
+        let (id, index) = u32::ssz_decode(bytes, index)?;
+        match id {
+            1 => {
+                let (block, index) = BlockGossip::ssz_decode(bytes, index)?;
+                Ok((PubsubMessage::Block(block), index))
+            }
+            2 => {
+                let (attestation, index) = AttestationGossip::ssz_decode(bytes, index)?;
+                Ok((PubsubMessage::Attestation(attestation), index))
+            }
+            _ => Err(DecodeError::Invalid),
+        }
+    }
+}
diff --git a/beacon_node/network/src/beacon_chain.rs b/beacon_node/network/src/beacon_chain.rs
index 26cea0065..c627912a4 100644
--- a/beacon_node/network/src/beacon_chain.rs
+++ b/beacon_node/network/src/beacon_chain.rs
@@ -109,7 +109,7 @@ where
         let state = self.get_state();
 
         HelloMessage {
-            network_id: spec.network_id,
+            network_id: spec.chain_id,
             latest_finalized_root: state.finalized_root,
             latest_finalized_epoch: state.finalized_epoch,
             best_root: self.best_block_root(),
diff --git a/beacon_node/network/src/service.rs b/beacon_node/network/src/service.rs
index a3eb6f0d9..33ea79c1a 100644
--- a/beacon_node/network/src/service.rs
+++ b/beacon_node/network/src/service.rs
@@ -3,7 +3,7 @@ use crate::error;
 use crate::message_handler::{HandlerMessage, MessageHandler};
 use crate::NetworkConfig;
 use crossbeam_channel::{unbounded as channel, Sender, TryRecvError};
-use eth2_libp2p::RPCEvent;
+use eth2_libp2p::{RPCEvent, PublishMessage};
 use eth2_libp2p::Service as LibP2PService;
 use eth2_libp2p::{Libp2pEvent, PeerId};
 use futures::prelude::*;
@@ -12,6 +12,7 @@ use futures::Stream;
 use slog::{debug, info, o, trace};
 use std::sync::Arc;
 use tokio::runtime::TaskExecutor;
+use types::{BeaconBlock, Topic};
 
 /// Service that handles communication between internal services and the eth2_libp2p network service.
 pub struct Service {
@@ -161,7 +162,12 @@ fn network_service(
                     return Err(eth2_libp2p::error::Error::from(
                         "Network channel disconnected",
                     ));
-                }
+                },
+            Ok(NetworkMessage::Publish(topic, message) => {
+                debug!(log, "Sending message on topic {:?}", topic);
+                libp2p_service.swarm.publish(topic,message)
+
+
             }
         }
         Ok(Async::NotReady)
@@ -174,6 +180,8 @@ pub enum NetworkMessage {
     /// Send a message to libp2p service.
     //TODO: Define typing for messages across the wire
     Send(PeerId, OutgoingMessage),
+    /// Publish a message to gossipsub
+    Publish(Topic, PublishMessage),
 }
 
 /// Type of outgoing messages that can be sent through the network service.
@@ -184,3 +192,4 @@ pub enum OutgoingMessage {
     //TODO: Remove
     NotifierTest,
 }
+
diff --git a/beacon_node/rpc/src/beacon_block.rs b/beacon_node/rpc/src/beacon_block.rs
index 96f64e0dd..9169d695d 100644
--- a/beacon_node/rpc/src/beacon_block.rs
+++ b/beacon_node/rpc/src/beacon_block.rs
@@ -9,6 +9,7 @@ use slog::Logger;
 
 #[derive(Clone)]
 pub struct BeaconBlockServiceInstance {
+    network_chan: crossbeam_channel::Sender<NetworkMessage>,
     pub log: Logger,
 }
 
@@ -43,7 +44,15 @@ impl BeaconBlockService for BeaconBlockServiceInstance {
         req: PublishBeaconBlockRequest,
         sink: UnarySink<PublishBeaconBlockResponse>,
     ) {
-        println!("publishing {:?}", req.get_block());
+        let block = req.get_block();
+        println!("publishing {:?}", block);
+
+
+        // TODO: Build properly
+        let topic = types::TopicBuilder::
+        println!("Sending beacon block to gossipsub");
+        network_chan.send(NetworkMessage::Publish(
+
 
         // TODO: actually process the block.
         let mut resp = PublishBeaconBlockResponse::new();
diff --git a/beacon_node/rpc/src/lib.rs b/beacon_node/rpc/src/lib.rs
index 3c89bda1f..e1267270c 100644
--- a/beacon_node/rpc/src/lib.rs
+++ b/beacon_node/rpc/src/lib.rs
@@ -21,6 +21,7 @@ use tokio::runtime::TaskExecutor;
 pub fn start_server(
     config: &RPCConfig,
     executor: &TaskExecutor,
+    network_chan: crossbeam_channel::Sender<NetworkMessage>,
     beacon_chain: Arc<BeaconChain>,
     log: &slog::Logger,
 ) -> exit_future::Signal {
@@ -40,7 +41,9 @@ pub fn start_server(
     };
 
     let beacon_block_service = {
-        let instance = BeaconBlockServiceInstance { log: log.clone() };
+        let instance = BeaconBlockServiceInstance {
+            network_chan
+            log: log.clone() };
         create_beacon_block_service(instance)
     };
     let validator_service = {