diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index cda247cb0..01b1bfabf 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -43,3 +43,4 @@ program](https://hackerone.com/tendermint).
 - [p2p] \#3338 Prevent "sent next PEX request too soon" errors by not calling
   ensurePeers outside of ensurePeersRoutine
 - [behaviour] Return correct reason in MessageOutOfOrder (@jim380)
+- [config] \#3723 Add consensus_params to testnet config generation; document time_iota_ms (@ashleyvega)
diff --git a/cmd/tendermint/commands/testnet.go b/cmd/tendermint/commands/testnet.go
index f1dd6f16e..5e2dc1a3a 100644
--- a/cmd/tendermint/commands/testnet.go
+++ b/cmd/tendermint/commands/testnet.go
@@ -161,9 +161,10 @@ func testnetFiles(cmd *cobra.Command, args []string) error {
 
 	// Generate genesis doc from generated validators
 	genDoc := &types.GenesisDoc{
-		GenesisTime: tmtime.Now(),
-		ChainID:     "chain-" + cmn.RandStr(6),
-		Validators:  genVals,
+		ChainID:         "chain-" + cmn.RandStr(6),
+		ConsensusParams: types.DefaultConsensusParams(),
+		GenesisTime:     tmtime.Now(),
+		Validators:      genVals,
 	}
 
 	// Write genesis file.
diff --git a/docs/tendermint-core/using-tendermint.md b/docs/tendermint-core/using-tendermint.md
index 05d481b2c..8c2fa1e03 100644
--- a/docs/tendermint-core/using-tendermint.md
+++ b/docs/tendermint-core/using-tendermint.md
@@ -43,6 +43,11 @@ definition](https://github.com/tendermint/tendermint/blob/master/types/genesis.g
 - `chain_id`: ID of the blockchain. This must be unique for
   every blockchain. If your testnet blockchains do not have unique
   chain IDs, you will have a bad time. The ChainID must be less than 50 symbols.
+- `consensus_params`
+  - `block`
+    - `time_iota_ms`: Minimum time increment between consecutive blocks (in
+      milliseconds). If the block header timestamp is ahead of the system clock,
+      decrease this value.
 - `validators`: List of initial validators. Note this may be overridden entirely by the
   application, and may be left empty to make explicit that the
   application will initialize the validator set with ResponseInitChain.
@@ -63,9 +68,10 @@ definition](https://github.com/tendermint/tendermint/blob/master/types/genesis.g
   "genesis_time": "2018-11-13T18:11:50.277637Z",
   "chain_id": "test-chain-s4ui7D",
   "consensus_params": {
-    "block_size": {
+    "block": {
       "max_bytes": "22020096",
-      "max_gas": "-1"
+      "max_gas": "-1",
+      "time_iota_ms": "1000"
     },
     "evidence": {
       "max_age": "100000"