diff --git a/eth2_node.py b/eth2_node.py
index 74c0e43..4397abd 100644
--- a/eth2_node.py
+++ b/eth2_node.py
@@ -57,6 +57,12 @@ def bn_produce_block(slot: Slot, randao_reveal: BLSSignature, graffiti: Bytes32)
     """
     pass
 
+def bn_submit_block(block: SignedBeaconBlock) -> None:
+    """Submit block to BN for p2p gossip.
+    Uses https://ethereum.github.io/beacon-APIs/#/ValidatorRequiredApi/publishBlock
+    """
+    pass
+
 
 # Validator Client Interface
 
diff --git a/spec.py b/spec.py
index 046b6df..d30f777 100644
--- a/spec.py
+++ b/spec.py
@@ -6,6 +6,7 @@
     bn_submit_attestation,
     bn_get_proposer_duties_for_epoch,
     bn_produce_block,
+    bn_submit_block,
     vc_is_slashable_attestation_data,
     vc_sign_attestation,
     vc_is_slashable_block,
@@ -61,8 +62,9 @@ def consensus_on_block(proposer_duty: ProposerDuty) -> AttestationData:
 """
 
 def serve_attestation_duty(attestation_duty):
-    # Obtain lock on consensus process here - only a single consensus instance
-    # should be running at any given time
+    # Obtain lock on consensus_on_attestation here.
+    # Only a single consensus_on_attestation instance should be
+    # running at any given time
     attestation_data = consensus_on_attestation(attestation_duty)
 
     # 1. Threshold sign attestation from local VC
@@ -73,7 +75,7 @@ def serve_attestation_duty(attestation_duty):
     # 4. Send complete signed attestation to BN for broadcast
     bn_submit_attestation(complete_signed_attestation)
 
-    # Release lock on consensus process here
+    # Release lock on consensus_on_attestation here.
 
 """
 Block Production Process:
@@ -87,4 +89,17 @@ def serve_attestation_duty(attestation_duty):
 """
 
 def serve_proposer_duty(proposer_duty):
-    pass
\ No newline at end of file
+    # Obtain lock on consensus_on_block here.
+    # Only a single consensus_on_block instance should be
+    # running at any given time
+    block = consensus_on_block(proposer_duty)
+
+    # 1. Threshold sign block from local VC
+    threshold_signed_block = vc_sign_block(block, proposer_duty)
+    # 2. Broadcast threshold signed block
+    # 3. Reconstruct complete signed block by combining threshold signed blocks
+    complete_signed_block = threshold_signed_block
+    # 4. Send complete signed block to BN for broadcast
+    bn_submit_block(complete_signed_block)
+
+    # Release lock on consensus_on_block here.
\ No newline at end of file