diff --git a/abci/client/client.go b/abci/client/client.go
index a46d83aa0..0c63d0ce5 100644
--- a/abci/client/client.go
+++ b/abci/client/client.go
@@ -43,6 +43,7 @@ type Client interface {
 	OfferSnapshotAsync(types.RequestOfferSnapshot) *ReqRes
 	LoadSnapshotChunkAsync(types.RequestLoadSnapshotChunk) *ReqRes
 	ApplySnapshotChunkAsync(types.RequestApplySnapshotChunk) *ReqRes
+	ProcessProposalAsync(types.RequestProcessProposal) *ReqRes
 
 	FlushSync() error
 	EchoSync(msg string) (*types.ResponseEcho, error)
@@ -60,6 +61,7 @@ type Client interface {
 	OfferSnapshotSync(types.RequestOfferSnapshot) (*types.ResponseOfferSnapshot, error)
 	LoadSnapshotChunkSync(types.RequestLoadSnapshotChunk) (*types.ResponseLoadSnapshotChunk, error)
 	ApplySnapshotChunkSync(types.RequestApplySnapshotChunk) (*types.ResponseApplySnapshotChunk, error)
+	ProcessProposalSync(types.RequestProcessProposal) (*types.ResponseProcessProposal, error)
 }
 
 //----------------------------------------
diff --git a/abci/client/grpc_client.go b/abci/client/grpc_client.go
index 38a7973d5..2034445b2 100644
--- a/abci/client/grpc_client.go
+++ b/abci/client/grpc_client.go
@@ -309,6 +309,28 @@ func (cli *grpcClient) PrepareProposalAsync(params types.RequestPrepareProposal)
 	return cli.finishAsyncCall(req, &types.Response{Value: &types.Response_PrepareProposal{PrepareProposal: res}})
 }
 
+func (cli *grpcClient) ProcessProposalAsync(
+	ctx context.Context,
+	params types.RequestProcessProposal,
+) (*ReqRes, error) {
+
+	req := types.ToRequestProcessProposal(params)
+	res, err := cli.client.ProcessProposal(ctx, req.GetProcessProposal(), grpc.WaitForReady(true))
+	if err != nil {
+		return nil, err
+	}
+
+	return cli.finishAsyncCall(
+		ctx,
+		req,
+		&types.Response{
+			Value: &types.Response_ProcessProposal{
+				ProcessProposal: res,
+			},
+		},
+	)
+}
+
 // finishAsyncCall creates a ReqRes for an async call, and immediately populates it
 // with the response. We don't complete it until it's been ordered via the channel.
 func (cli *grpcClient) finishAsyncCall(req *types.Request, res *types.Response) *ReqRes {
@@ -432,3 +454,15 @@ func (cli *grpcClient) PrepareProposalSync(
 	reqres := cli.PrepareProposalAsync(params)
 	return cli.finishSyncCall(reqres).GetPrepareProposal(), cli.Error()
 }
+
+func (cli *grpcClient) ProcessProposalSync(
+	ctx context.Context,
+	params types.RequestProcessProposal,
+) (*types.ResponseProcessProposal, error) {
+
+	reqres, err := cli.ProcessProposalAsync(ctx, params)
+	if err != nil {
+		return nil, err
+	}
+	return cli.finishSyncCall(reqres).GetProcessProposal(), cli.Error()
+}
diff --git a/abci/client/local_client.go b/abci/client/local_client.go
index e33e68ca2..e2773aa32 100644
--- a/abci/client/local_client.go
+++ b/abci/client/local_client.go
@@ -218,6 +218,20 @@ func (app *localClient) PrepareProposalAsync(req types.RequestPrepareProposal) *
 	)
 }
 
+func (app *localClient) ProcessProposalAsync(
+	ctx context.Context,
+	req types.RequestProcessProposal,
+) (*ReqRes, error) {
+	app.mtx.Lock()
+	defer app.mtx.Unlock()
+
+	res := app.Application.ProcessProposal(req)
+	return app.callback(
+		types.ToRequestProcessProposal(req),
+		types.ToResponseProcessProposal(res),
+	), nil
+}
+
 //-------------------------------------------------------
 
 func (app *localClient) FlushSync() error {
@@ -342,6 +356,17 @@ func (app *localClient) PrepareProposalSync(req types.RequestPrepareProposal) (*
 	return &res, nil
 }
 
+func (app *localClient) ProcessProposalSync(
+	ctx context.Context,
+	req types.RequestProcessProposal,
+) (*types.ResponseProcessProposal, error) {
+	app.mtx.Lock()
+	defer app.mtx.Unlock()
+
+	res := app.Application.ProcessProposal(req)
+	return &res, nil
+}
+
 //-------------------------------------------------------
 
 func (app *localClient) callback(req *types.Request, res *types.Response) *ReqRes {
diff --git a/abci/client/socket_client.go b/abci/client/socket_client.go
index dd1c556c2..cea929c8c 100644
--- a/abci/client/socket_client.go
+++ b/abci/client/socket_client.go
@@ -283,6 +283,13 @@ func (cli *socketClient) PrepareProposalAsync(req types.RequestPrepareProposal)
 	return cli.queueRequest(types.ToRequestPrepareProposal(req))
 }
 
+func (cli *socketClient) ProcessProposalAsync(
+	ctx context.Context,
+	req types.RequestProcessProposal,
+) (*ReqRes, error) {
+	return cli.queueRequestAsync(ctx, types.ToRequestProcessProposal(req))
+}
+
 //----------------------------------------
 
 func (cli *socketClient) FlushSync() error {
@@ -430,6 +437,18 @@ func (cli *socketClient) PrepareProposalSync(req types.RequestPrepareProposal) (
 	return reqres.Response.GetPrepareProposal(), cli.Error()
 }
 
+func (cli *socketClient) ProcessProposalSync(
+	ctx context.Context,
+	req types.RequestProcessProposal,
+) (*types.ResponseProcessProposal, error) {
+
+	reqres, err := cli.queueRequestAndFlushSync(ctx, types.ToRequestProcessProposal(req))
+	if err != nil {
+		return nil, err
+	}
+	return reqres.Response.GetProcessProposal(), nil
+}
+
 //----------------------------------------
 
 func (cli *socketClient) queueRequest(req *types.Request) *ReqRes {
diff --git a/abci/example/kvstore/persistent_kvstore.go b/abci/example/kvstore/persistent_kvstore.go
index 320f25502..14a6c93e9 100644
--- a/abci/example/kvstore/persistent_kvstore.go
+++ b/abci/example/kvstore/persistent_kvstore.go
@@ -179,6 +179,16 @@ func (app *PersistentKVStoreApplication) PrepareProposal(
 	return types.ResponsePrepareProposal{BlockData: req.BlockData}
 }
 
+func (app *PersistentKVStoreApplication) ProcessProposal(
+	req types.RequestProcessProposal) types.ResponseProcessProposal {
+	for _, tx := range req.Txs {
+		if len(tx) == 0 {
+			return types.ResponseProcessProposal{Result: types.ResponseProcessProposal_REJECT}
+		}
+	}
+	return types.ResponseProcessProposal{Result: types.ResponseProcessProposal_ACCEPT}
+}
+
 //---------------------------------------------
 // update validators
 
diff --git a/abci/types/application.go b/abci/types/application.go
index fe69b6f05..576480ace 100644
--- a/abci/types/application.go
+++ b/abci/types/application.go
@@ -24,6 +24,7 @@ type Application interface {
 	DeliverTx(RequestDeliverTx) ResponseDeliverTx    // Deliver a tx for full processing
 	EndBlock(RequestEndBlock) ResponseEndBlock       // Signals the end of a block, returns changes to the validator set
 	Commit() ResponseCommit                          // Commit the state and return the application Merkle root hash
+	ProcessProposal(RequestProcessProposal) ResponseProcessProposal
 
 	// State Sync Connection
 	ListSnapshots(RequestListSnapshots) ResponseListSnapshots                // List available snapshots
@@ -102,6 +103,10 @@ func (BaseApplication) PrepareProposal(req RequestPrepareProposal) ResponsePrepa
 	}
 }
 
+func (BaseApplication) ProcessProposal(req RequestProcessProposal) ResponseProcessProposal {
+	return ResponseProcessProposal{}
+}
+
 //-------------------------------------------------------
 
 // GRPCApplication is a GRPC wrapper for Application
@@ -195,3 +200,9 @@ func (app *GRPCApplication) PrepareProposal(
 	res := app.app.PrepareProposal(*req)
 	return &res, nil
 }
+
+func (app *GRPCApplication) ProcessProposal(
+	ctx context.Context, req *RequestProcessProposal) (*ResponseProcessProposal, error) {
+	res := app.app.ProcessProposal(*req)
+	return &res, nil
+}
diff --git a/abci/types/messages.go b/abci/types/messages.go
index 599e8c05f..4314b5bfc 100644
--- a/abci/types/messages.go
+++ b/abci/types/messages.go
@@ -165,6 +165,12 @@ func ToRequestPrepareProposal(req RequestPrepareProposal) *Request {
 	}
 }
 
+func ToRequestProcessProposal(req RequestProcessProposal) *Request {
+	return &Request{
+		Value: &Request_ProcessProposal{&req},
+	}
+}
+
 //----------------------------------------
 
 func ToResponseException(errStr string) *Response {
@@ -268,3 +274,9 @@ func ToResponsePrepareProposal(res ResponsePrepareProposal) *Response {
 		Value: &Response_PrepareProposal{&res},
 	}
 }
+
+func ToResponseProcessProposal(res ResponseProcessProposal) *Response {
+	return &Response{
+		Value: &Response_ProcessProposal{&res},
+	}
+}
diff --git a/abci/types/result.go b/abci/types/result.go
index 53acdb906..d29910a83 100644
--- a/abci/types/result.go
+++ b/abci/types/result.go
@@ -41,6 +41,21 @@ func (r ResponseQuery) IsErr() bool {
 	return r.Code != CodeTypeOK
 }
 
+// IsUnknown returns true if Code is Unknown
+func (r ResponseProcessProposal) IsUnknown() bool {
+	return r.Result == ResponseProcessProposal_UNKNOWN
+}
+
+// IsOK returns true if Code is OK
+func (r ResponseProcessProposal) IsOK() bool {
+	return r.Result == ResponseProcessProposal_ACCEPT
+}
+
+// IsErr returns true if Code is something other than OK.
+func (r ResponseProcessProposal) IsErr() bool {
+	return r.Result != ResponseProcessProposal_ACCEPT
+}
+
 //---------------------------------------------------------------------------
 // override JSON marshaling so we emit defaults (ie. disable omitempty)
 
diff --git a/consensus/byzantine_test.go b/consensus/byzantine_test.go
index dd5febcbd..a207c172e 100644
--- a/consensus/byzantine_test.go
+++ b/consensus/byzantine_test.go
@@ -223,7 +223,7 @@ func TestByzantinePrevoteEquivocation(t *testing.T) {
 
 		// Make proposal
 		propBlockID := types.BlockID{Hash: block.Hash(), PartSetHeader: blockParts.Header()}
-		proposal := types.NewProposal(height, round, lazyProposer.ValidRound, propBlockID)
+		proposal := types.NewProposal(height, round, lazyProposer.TwoThirdPrevoteRound, propBlockID)
 		p := proposal.ToProto()
 		if err := lazyProposer.privValidator.SignProposal(lazyProposer.state.ChainID, p); err == nil {
 			proposal.Signature = p.Signature
@@ -462,7 +462,7 @@ func byzantineDecideProposalFunc(t *testing.T, height int64, round int32, cs *St
 
 	// Create a new proposal block from state/txs from the mempool.
 	block1, blockParts1 := cs.createProposalBlock()
-	polRound, propBlockID := cs.ValidRound, types.BlockID{Hash: block1.Hash(), PartSetHeader: blockParts1.Header()}
+	polRound, propBlockID := cs.TwoThirdPrevoteRound, types.BlockID{Hash: block1.Hash(), PartSetHeader: blockParts1.Header()}
 	proposal1 := types.NewProposal(height, round, polRound, propBlockID)
 	p1 := proposal1.ToProto()
 	if err := cs.privValidator.SignProposal(cs.state.ChainID, p1); err != nil {
@@ -476,7 +476,7 @@ func byzantineDecideProposalFunc(t *testing.T, height int64, round int32, cs *St
 
 	// Create a new proposal block from state/txs from the mempool.
 	block2, blockParts2 := cs.createProposalBlock()
-	polRound, propBlockID = cs.ValidRound, types.BlockID{Hash: block2.Hash(), PartSetHeader: blockParts2.Header()}
+	polRound, propBlockID = cs.TwoThirdPrevoteRound, types.BlockID{Hash: block2.Hash(), PartSetHeader: blockParts2.Header()}
 	proposal2 := types.NewProposal(height, round, polRound, propBlockID)
 	p2 := proposal2.ToProto()
 	if err := cs.privValidator.SignProposal(cs.state.ChainID, p2); err != nil {
diff --git a/consensus/common_test.go b/consensus/common_test.go
index 09512f49d..4722e1600 100644
--- a/consensus/common_test.go
+++ b/consensus/common_test.go
@@ -208,7 +208,7 @@ func decideProposal(
 ) (proposal *types.Proposal, block *types.Block) {
 	cs1.mtx.Lock()
 	block, blockParts := cs1.createProposalBlock()
-	validRound := cs1.ValidRound
+	validRound := cs1.TwoThirdPrevoteRound
 	chainID := cs1.state.ChainID
 	cs1.mtx.Unlock()
 	if block == nil {
diff --git a/consensus/state.go b/consensus/state.go
index 9e6d980a3..17a02bcd1 100644
--- a/consensus/state.go
+++ b/consensus/state.go
@@ -667,9 +667,9 @@ func (cs *State) updateToState(state sm.State) {
 	cs.LockedRound = -1
 	cs.LockedBlock = nil
 	cs.LockedBlockParts = nil
-	cs.ValidRound = -1
-	cs.ValidBlock = nil
-	cs.ValidBlockParts = nil
+	cs.TwoThirdPrevoteRound = -1
+	cs.TwoThirdPrevoteBlock = nil
+	cs.TwoThirdPrevoteBlockParts = nil
 	cs.Votes = cstypes.NewHeightVoteSet(state.ChainID, height, validators)
 	cs.CommitRound = -1
 	cs.LastValidators = state.LastValidators
@@ -1126,9 +1126,9 @@ func (cs *State) defaultDecideProposal(height int64, round int32) {
 	var blockParts *types.PartSet
 
 	// Decide on block
-	if cs.ValidBlock != nil {
+	if cs.TwoThirdPrevoteBlock != nil {
 		// If there is valid block, choose that.
-		block, blockParts = cs.ValidBlock, cs.ValidBlockParts
+		block, blockParts = cs.TwoThirdPrevoteBlock, cs.TwoThirdPrevoteBlockParts
 	} else {
 		// Create a new proposal block from state/txs from the mempool.
 		block, blockParts = cs.createProposalBlock()
@@ -1145,7 +1145,7 @@ func (cs *State) defaultDecideProposal(height int64, round int32) {
 
 	// Make proposal
 	propBlockID := types.BlockID{Hash: block.Hash(), PartSetHeader: blockParts.Header()}
-	proposal := types.NewProposal(height, round, cs.ValidRound, propBlockID)
+	proposal := types.NewProposal(height, round, cs.TwoThirdPrevoteRound, propBlockID)
 	p := proposal.ToProto()
 	if err := cs.privValidator.SignProposal(cs.state.ChainID, p); err == nil {
 		proposal.Signature = p.Signature
@@ -1276,6 +1276,19 @@ func (cs *State) defaultDoPrevote(height int64, round int32) {
 		return
 	}
 
+	stateMachineValidBlock, err := cs.blockExec.ProcessProposal(cs.ProposalBlock)
+	if err != nil {
+		cs.Logger.Error("state machine returned an error when trying to process proposal block", "err", err)
+	}
+
+	// Vote nil if application invalidated the block
+	if !stateMachineValidBlock {
+		// Consensus says we must vote nil
+		logger.Error("prevote step: consensus deems this block to be mustVoteNil", "err", err)
+		cs.signAddVote(tmproto.PrevoteType, nil, types.PartSetHeader{})
+		return
+	}
+
 	// Prevote cs.ProposalBlock
 	// NOTE: the proposal signature is validated when it is received,
 	// and the proposal block parts are validated as they are received (against the merkle hash in the proposal)
@@ -1913,7 +1926,7 @@ func (cs *State) handleCompleteProposal(blockHeight int64) {
 	// Update Valid* if we can.
 	prevotes := cs.Votes.Prevotes(cs.Round)
 	blockID, hasTwoThirds := prevotes.TwoThirdsMajority()
-	if hasTwoThirds && !blockID.IsZero() && (cs.ValidRound < cs.Round) {
+	if hasTwoThirds && !blockID.IsZero() && (cs.TwoThirdPrevoteRound < cs.Round) {
 		if cs.ProposalBlock.HashesTo(blockID.Hash) {
 			cs.Logger.Debug(
 				"updating valid block to new proposal block",
@@ -1921,9 +1934,9 @@ func (cs *State) handleCompleteProposal(blockHeight int64) {
 				"valid_block_hash", log.NewLazyBlockHash(cs.ProposalBlock),
 			)
 
-			cs.ValidRound = cs.Round
-			cs.ValidBlock = cs.ProposalBlock
-			cs.ValidBlockParts = cs.ProposalBlockParts
+			cs.TwoThirdPrevoteRound = cs.Round
+			cs.TwoThirdPrevoteBlock = cs.ProposalBlock
+			cs.TwoThirdPrevoteBlockParts = cs.ProposalBlockParts
 		}
 		// TODO: In case there is +2/3 majority in Prevotes set for some
 		// block and cs.ProposalBlock contains different block, either
@@ -2083,12 +2096,12 @@ func (cs *State) addVote(vote *types.Vote, peerID p2p.ID) (added bool, err error
 
 			// Update Valid* if we can.
 			// NOTE: our proposal block may be nil or not what received a polka..
-			if len(blockID.Hash) != 0 && (cs.ValidRound < vote.Round) && (vote.Round == cs.Round) {
+			if len(blockID.Hash) != 0 && (cs.TwoThirdPrevoteRound < vote.Round) && (vote.Round == cs.Round) {
 				if cs.ProposalBlock.HashesTo(blockID.Hash) {
-					cs.Logger.Debug("updating valid block because of POL", "valid_round", cs.ValidRound, "pol_round", vote.Round)
-					cs.ValidRound = vote.Round
-					cs.ValidBlock = cs.ProposalBlock
-					cs.ValidBlockParts = cs.ProposalBlockParts
+					cs.Logger.Debug("updating valid block because of POL", "valid_round", cs.TwoThirdPrevoteRound, "pol_round", vote.Round)
+					cs.TwoThirdPrevoteRound = vote.Round
+					cs.TwoThirdPrevoteBlock = cs.ProposalBlock
+					cs.TwoThirdPrevoteBlockParts = cs.ProposalBlockParts
 				} else {
 					cs.Logger.Debug(
 						"valid block we do not know about; set ProposalBlock=nil",
diff --git a/consensus/state_test.go b/consensus/state_test.go
index 1e3887fd9..8403f4950 100644
--- a/consensus/state_test.go
+++ b/consensus/state_test.go
@@ -1199,9 +1199,9 @@ func TestProposeValidBlock(t *testing.T) {
 
 	rs = cs1.GetRoundState()
 	assert.True(t, bytes.Equal(rs.ProposalBlock.Hash(), propBlockHash))
-	assert.True(t, bytes.Equal(rs.ProposalBlock.Hash(), rs.ValidBlock.Hash()))
-	assert.True(t, rs.Proposal.POLRound == rs.ValidRound)
-	assert.True(t, bytes.Equal(rs.Proposal.BlockID.Hash, rs.ValidBlock.Hash()))
+	assert.True(t, bytes.Equal(rs.ProposalBlock.Hash(), rs.TwoThirdPrevoteBlock.Hash()))
+	assert.True(t, rs.Proposal.POLRound == rs.TwoThirdPrevoteRound)
+	assert.True(t, bytes.Equal(rs.Proposal.BlockID.Hash, rs.TwoThirdPrevoteBlock.Hash()))
 }
 
 // What we want:
@@ -1249,9 +1249,9 @@ func TestSetValidBlockOnDelayedPrevote(t *testing.T) {
 
 	rs = cs1.GetRoundState()
 
-	assert.True(t, rs.ValidBlock == nil)
-	assert.True(t, rs.ValidBlockParts == nil)
-	assert.True(t, rs.ValidRound == -1)
+	assert.True(t, rs.TwoThirdPrevoteBlock == nil)
+	assert.True(t, rs.TwoThirdPrevoteBlockParts == nil)
+	assert.True(t, rs.TwoThirdPrevoteRound == -1)
 
 	// vs2 send (delayed) prevote for propBlock
 	signAddVotes(cs1, tmproto.PrevoteType, propBlockHash, propBlockParts.Header(), vs4)
@@ -1260,9 +1260,9 @@ func TestSetValidBlockOnDelayedPrevote(t *testing.T) {
 
 	rs = cs1.GetRoundState()
 
-	assert.True(t, bytes.Equal(rs.ValidBlock.Hash(), propBlockHash))
-	assert.True(t, rs.ValidBlockParts.Header().Equals(propBlockParts.Header()))
-	assert.True(t, rs.ValidRound == round)
+	assert.True(t, bytes.Equal(rs.TwoThirdPrevoteBlock.Hash(), propBlockHash))
+	assert.True(t, rs.TwoThirdPrevoteBlockParts.Header().Equals(propBlockParts.Header()))
+	assert.True(t, rs.TwoThirdPrevoteRound == round)
 }
 
 // What we want:
@@ -1316,9 +1316,9 @@ func TestSetValidBlockOnDelayedProposal(t *testing.T) {
 	ensureNewProposal(proposalCh, height, round)
 	rs := cs1.GetRoundState()
 
-	assert.True(t, bytes.Equal(rs.ValidBlock.Hash(), propBlockHash))
-	assert.True(t, rs.ValidBlockParts.Header().Equals(propBlockParts.Header()))
-	assert.True(t, rs.ValidRound == round)
+	assert.True(t, bytes.Equal(rs.TwoThirdPrevoteBlock.Hash(), propBlockHash))
+	assert.True(t, rs.TwoThirdPrevoteBlockParts.Header().Equals(propBlockParts.Header()))
+	assert.True(t, rs.TwoThirdPrevoteRound == round)
 }
 
 // 4 vals, 3 Nil Precommits at P0
diff --git a/consensus/types/round_state.go b/consensus/types/round_state.go
index 9e67b76c0..3b11c2e17 100644
--- a/consensus/types/round_state.go
+++ b/consensus/types/round_state.go
@@ -81,11 +81,11 @@ type RoundState struct {
 	LockedBlockParts   *types.PartSet      `json:"locked_block_parts"`
 
 	// Last known round with POL for non-nil valid block.
-	ValidRound int32        `json:"valid_round"`
-	ValidBlock *types.Block `json:"valid_block"` // Last known block of POL mentioned above.
+	TwoThirdPrevoteRound int32        `json:"valid_round"`
+	TwoThirdPrevoteBlock *types.Block `json:"valid_block"` // Last known block of POL mentioned above.
 
 	// Last known block parts of POL mentioned above.
-	ValidBlockParts           *types.PartSet      `json:"valid_block_parts"`
+	TwoThirdPrevoteBlockParts *types.PartSet      `json:"valid_block_parts"`
 	Votes                     *HeightVoteSet      `json:"votes"`
 	CommitRound               int32               `json:"commit_round"` //
 	LastCommit                *types.VoteSet      `json:"last_commit"`  // Last precommits at Height-1
@@ -119,7 +119,7 @@ func (rs *RoundState) RoundStateSimple() RoundStateSimple {
 		StartTime:         rs.StartTime,
 		ProposalBlockHash: rs.ProposalBlock.Hash(),
 		LockedBlockHash:   rs.LockedBlock.Hash(),
-		ValidBlockHash:    rs.ValidBlock.Hash(),
+		ValidBlockHash:    rs.TwoThirdPrevoteBlock.Hash(),
 		Votes:             votesJSON,
 		Proposer: types.ValidatorInfo{
 			Address: addr,
@@ -186,8 +186,8 @@ func (rs *RoundState) StringIndented(indent string) string {
 %s  ProposalBlock: %v %v
 %s  LockedRound:   %v
 %s  LockedBlock:   %v %v
-%s  ValidRound:   %v
-%s  ValidBlock:   %v %v
+%s  TwoThirdPrevoteRound:   %v
+%s  TwoThirdPrevoteBlock:   %v %v
 %s  Votes:         %v
 %s  LastCommit:    %v
 %s  LastValidators:%v
@@ -200,8 +200,8 @@ func (rs *RoundState) StringIndented(indent string) string {
 		indent, rs.ProposalBlockParts.StringShort(), rs.ProposalBlock.StringShort(),
 		indent, rs.LockedRound,
 		indent, rs.LockedBlockParts.StringShort(), rs.LockedBlock.StringShort(),
-		indent, rs.ValidRound,
-		indent, rs.ValidBlockParts.StringShort(), rs.ValidBlock.StringShort(),
+		indent, rs.TwoThirdPrevoteRound,
+		indent, rs.TwoThirdPrevoteBlockParts.StringShort(), rs.TwoThirdPrevoteBlock.StringShort(),
 		indent, rs.Votes.StringIndented(indent+"  "),
 		indent, rs.LastCommit.StringShort(),
 		indent, rs.LastValidators.StringIndented(indent+"  "),
diff --git a/proto/tendermint/abci/types.proto b/proto/tendermint/abci/types.proto
index fc3228280..9415a2804 100644
--- a/proto/tendermint/abci/types.proto
+++ b/proto/tendermint/abci/types.proto
@@ -37,6 +37,7 @@ message Request {
     RequestLoadSnapshotChunk  load_snapshot_chunk  = 14;
     RequestApplySnapshotChunk apply_snapshot_chunk = 15;
     RequestPrepareProposal    prepare_proposal     = 16;
+    RequestProcessProposal    process_proposal     = 17;
   }
 }
 
@@ -134,6 +135,11 @@ message RequestPrepareProposal {
   int64 block_data_size = 2;
 }
 
+message RequestProcessProposal {
+  tendermint.types.Header header = 1 [(gogoproto.nullable) = false];
+  repeated bytes txs = 2;
+}
+
 //----------------------------------------
 // Response types
 
@@ -156,7 +162,7 @@ message Response {
     ResponseLoadSnapshotChunk  load_snapshot_chunk  = 15;
     ResponseApplySnapshotChunk apply_snapshot_chunk = 16;
     ResponsePrepareProposal    prepare_proposal     = 17;
-
+    ResponseProcessProposal    process_proposal     = 18;
   }
 }
 
@@ -298,6 +304,17 @@ message ResponsePrepareProposal {
   repeated bytes block_data = 1;
 }
 
+message ResponseProcessProposal {
+  Result result = 1;
+  repeated bytes evidence = 2;
+
+  enum Result {
+    UNKNOWN       = 0;  // Unknown result, invalidate
+    ACCEPT        = 1;  // proposal verified, vote on the proposal
+    REJECT        = 2;  // proposal invalidated
+  }
+}
+
 //----------------------------------------
 // Misc.
 
@@ -427,4 +444,5 @@ service ABCIApplication {
   rpc ApplySnapshotChunk(RequestApplySnapshotChunk)
       returns (ResponseApplySnapshotChunk);
   rpc PrepareProposal(RequestPrepareProposal) returns (ResponsePrepareProposal);
+  rpc ProcessProposal(RequestProcessProposal) returns (ResponseProcessProposal);
 }
diff --git a/proxy/app_conn.go b/proxy/app_conn.go
index 5a08f2d1a..9614767cb 100644
--- a/proxy/app_conn.go
+++ b/proxy/app_conn.go
@@ -15,8 +15,8 @@ type AppConnConsensus interface {
 	Error() error
 
 	InitChainSync(types.RequestInitChain) (*types.ResponseInitChain, error)
-
 	PrepareProposalSync(types.RequestPrepareProposal) (*types.ResponsePrepareProposal, error)
+	ProcessProposalSync(types.RequestProcessProposal) (*types.ResponseProcessProposal, error)
 	BeginBlockSync(types.RequestBeginBlock) (*types.ResponseBeginBlock, error)
 	DeliverTxAsync(types.RequestDeliverTx) *abcicli.ReqRes
 	EndBlockSync(types.RequestEndBlock) (*types.ResponseEndBlock, error)
@@ -85,6 +85,10 @@ func (app *appConnConsensus) PrepareProposalSync(
 	return app.appConn.PrepareProposalSync(req)
 }
 
+func (app *appConnConsensus) ProcessProposalSync(req types.RequestProcessProposal) (*types.ResponseProcessProposal, error) {
+	return app.appConn.ProcessProposalSync(req)
+}
+
 func (app *appConnConsensus) BeginBlockSync(req types.RequestBeginBlock) (*types.ResponseBeginBlock, error) {
 	return app.appConn.BeginBlockSync(req)
 }
diff --git a/state/execution.go b/state/execution.go
index a6451146d..7f292c3af 100644
--- a/state/execution.go
+++ b/state/execution.go
@@ -138,6 +138,23 @@ func (blockExec *BlockExecutor) CreateProposalBlock(
 	return state.MakeBlock(height, modifiedTxs, commit, evidence, proposerAddr)
 }
 
+func (blockExec *BlockExecutor) ProcessProposal(
+	block *types.Block,
+) (bool, error) {
+	ctx := context.Background()
+	req := abci.RequestProcessProposal{
+		Txs:    block.Data.Txs.ToSliceOfBytes(),
+		Header: *block.Header.ToProto(),
+	}
+
+	resp, err := blockExec.proxyApp.ProcessProposalSync(ctx, req)
+	if err != nil {
+		return false, ErrInvalidBlock(err)
+	}
+
+	return resp.IsOK(), nil
+}
+
 // ValidateBlock validates the given block against the given state.
 // If the block is invalid, it returns an error.
 // Validation does not mutate state, but does require historical information from the stateDB,
diff --git a/state/execution_test.go b/state/execution_test.go
index cfde97f92..9527407fb 100644
--- a/state/execution_test.go
+++ b/state/execution_test.go
@@ -14,6 +14,7 @@ import (
 	"github.com/tendermint/tendermint/crypto/ed25519"
 	cryptoenc "github.com/tendermint/tendermint/crypto/encoding"
 	"github.com/tendermint/tendermint/crypto/tmhash"
+	sf "github.com/tendermint/tendermint/internal/test/factory"
 	"github.com/tendermint/tendermint/libs/log"
 	mmock "github.com/tendermint/tendermint/mempool/mock"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
@@ -22,9 +23,11 @@ import (
 	sm "github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/state/mocks"
 	sf "github.com/tendermint/tendermint/state/test/factory"
+	"github.com/tendermint/tendermint/store"
 	"github.com/tendermint/tendermint/types"
 	tmtime "github.com/tendermint/tendermint/types/time"
 	"github.com/tendermint/tendermint/version"
+	dbm "github.com/tendermint/tm-db"
 )
 
 var (
@@ -214,6 +217,38 @@ func TestBeginBlockByzantineValidators(t *testing.T) {
 	assert.Equal(t, abciEv, app.ByzantineValidators)
 }
 
+func TestProcessProposal(t *testing.T) {
+	height := 1
+	runTest := func(txs types.Txs, expectAccept bool) {
+		app := &testApp{}
+		cc := proxy.NewLocalClientCreator(app)
+		proxyApp := proxy.NewAppConns(cc)
+		err := proxyApp.Start()
+		require.Nil(t, err)
+		defer proxyApp.Stop() //nolint:errcheck // ignore for tests
+
+		state, stateDB, _ := makeState(1, height)
+		stateStore := sm.NewStore(stateDB)
+
+		blockStore := store.NewBlockStore(dbm.NewMemDB())
+
+		blockExec := sm.NewBlockExecutor(stateStore, log.TestingLogger(), proxyApp.Consensus(),
+			mmock.Mempool{}, sm.EmptyEvidencePool{}, blockStore)
+
+		block := sf.MakeBlock(state, int64(height), new(types.Commit))
+		block.Txs = txs
+		acceptBlock, err := blockExec.ProcessProposal(block)
+		require.Nil(t, err)
+		require.Equal(t, expectAccept, acceptBlock)
+	}
+	goodTxs := sf.MakeTenTxs(int64(height))
+	runTest(goodTxs, true)
+	// testApp has process proposal fail if any tx is 0-len
+	badTxs := sf.MakeTenTxs(int64(height))
+	badTxs[0] = types.Tx{}
+	runTest(badTxs, false)
+}
+
 func TestValidateValidatorUpdates(t *testing.T) {
 	pubkey1 := ed25519.GenPrivKey().PubKey()
 	pubkey2 := ed25519.GenPrivKey().PubKey()
diff --git a/state/helpers_test.go b/state/helpers_test.go
index 8945ed506..471533769 100644
--- a/state/helpers_test.go
+++ b/state/helpers_test.go
@@ -256,3 +256,12 @@ func (app *testApp) Commit() abci.ResponseCommit {
 func (app *testApp) Query(reqQuery abci.RequestQuery) (resQuery abci.ResponseQuery) {
 	return
 }
+
+func (app *testApp) ProcessProposal(req abci.RequestProcessProposal) abci.ResponseProcessProposal {
+	for _, tx := range req.Txs {
+		if len(tx) == 0 {
+			return abci.ResponseProcessProposal{Result: abci.ResponseProcessProposal_REJECT}
+		}
+	}
+	return abci.ResponseProcessProposal{Result: abci.ResponseProcessProposal_ACCEPT}
+}