diff --git a/beacon_chain/rpc/rest_beacon_api.nim b/beacon_chain/rpc/rest_beacon_api.nim
index 8fd2a1e7b..c70d15c9f 100644
--- a/beacon_chain/rpc/rest_beacon_api.nim
+++ b/beacon_chain/rpc/rest_beacon_api.nim
@@ -856,7 +856,8 @@ proc installBeaconApiHandlers*(router: var RestRouter, node: BeaconNode) =
     of ConsensusFork.Bellatrix:
       let res =
         block:
-          let restBlock = decodeBodyJsonOrSsz(SignedBlindedBeaconBlock, body).valueOr:
+          let restBlock = decodeBodyJsonOrSsz(
+              bellatrix_mev.SignedBlindedBeaconBlock, body).valueOr:
             return RestApiResponse.jsonError(Http400, InvalidBlockObjectError,
                                              $error)
           await node.unblindAndRouteBlockMEV(restBlock)
diff --git a/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim b/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
index a4bc3dbb9..3cba7eec9 100644
--- a/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
+++ b/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
@@ -13,7 +13,7 @@ import stew/[assign2, results, base10, byteutils], presto/common,
 import ".."/[eth2_ssz_serialization, forks, keystore],
        ".."/../consensus_object_pools/block_pools_types,
        ".."/datatypes/[phase0, altair, bellatrix],
-       ".."/mev/bellatrix_mev,
+       ".."/mev/[bellatrix_mev, capella_mev],
        ".."/../validators/slashing_protection_common,
        "."/[rest_types, rest_keymanager_types]
 import nimcrypto/utils as ncrutils
@@ -85,7 +85,8 @@ type
     PrepareBeaconProposer |
     ProposerSlashing |
     SetFeeRecipientRequest |
-    SignedBlindedBeaconBlock |
+    bellatrix_mev.SignedBlindedBeaconBlock |
+    capella_mev.SignedBlindedBeaconBlock |
     SignedValidatorRegistrationV1 |
     SignedVoluntaryExit |
     Web3SignerRequest
diff --git a/beacon_chain/spec/eth2_apis/rest_beacon_calls.nim b/beacon_chain/spec/eth2_apis/rest_beacon_calls.nim
index 4941bafc1..1e3bd3711 100644
--- a/beacon_chain/spec/eth2_apis/rest_beacon_calls.nim
+++ b/beacon_chain/spec/eth2_apis/rest_beacon_calls.nim
@@ -143,7 +143,8 @@ proc publishBlindedBlock*(body: altair.SignedBeaconBlock): RestPlainResponse {.
      meth: MethodPost.}
   ## https://ethereum.github.io/beacon-APIs/#/Beacon/publishBlindedBlock
 
-proc publishBlindedBlock*(body: SignedBlindedBeaconBlock): RestPlainResponse {.
+proc publishBlindedBlock*(body: bellatrix_mev.SignedBlindedBeaconBlock):
+       RestPlainResponse {.
      rest, endpoint: "/eth/v1/beacon/blinded_blocks",
      meth: MethodPost.}
   ## https://ethereum.github.io/beacon-APIs/#/Beacon/publishBlindedBlock
diff --git a/beacon_chain/spec/eth2_apis/rest_types.nim b/beacon_chain/spec/eth2_apis/rest_types.nim
index 042db48cf..381f16768 100644
--- a/beacon_chain/spec/eth2_apis/rest_types.nim
+++ b/beacon_chain/spec/eth2_apis/rest_types.nim
@@ -18,11 +18,11 @@ import
   stew/base10, web3/ethtypes,
   ".."/forks,
   ".."/datatypes/[phase0, altair, bellatrix, eip4844],
-  ".."/mev/bellatrix_mev
+  ".."/mev/[bellatrix_mev, capella_mev]
 
 from ".."/datatypes/capella import BeaconBlockBody
 
-export forks, phase0, altair, bellatrix, capella, bellatrix_mev
+export forks, phase0, altair, bellatrix, capella, bellatrix_mev, capella_mev
 
 const
   # https://github.com/ethereum/eth2.0-APIs/blob/master/apis/beacon/states/validator_balances.yaml#L17
@@ -633,7 +633,7 @@ type
   GetEpochCommitteesResponse* = DataEnclosedObject[seq[RestBeaconStatesCommittees]]
   GetForkScheduleResponse* = DataEnclosedObject[seq[Fork]]
   GetGenesisResponse* = DataEnclosedObject[RestGenesis]
-  GetHeaderResponse* = DataVersionEnclosedObject[SignedBuilderBid]
+  GetHeaderResponse* = DataVersionEnclosedObject[bellatrix_mev.SignedBuilderBid]
   GetNetworkIdentityResponse* = DataEnclosedObject[RestNetworkIdentity]
   GetPeerCountResponse* = DataMetaEnclosedObject[RestPeerCount]
   GetPeerResponse* = DataMetaEnclosedObject[RestNodePeer]
@@ -659,7 +659,8 @@ type
   ProduceBlockResponseV2* = ForkedBeaconBlock
   ProduceBlindedBlockResponse* = ForkedBlindedBeaconBlock
   ProduceSyncCommitteeContributionResponse* = DataEnclosedObject[SyncCommitteeContribution]
-  SubmitBlindedBlockResponse* = DataEnclosedObject[bellatrix.ExecutionPayload]
+  SubmitBlindedBlockResponseBellatrix* = DataEnclosedObject[bellatrix.ExecutionPayload]
+  SubmitBlindedBlockResponseCapella* = DataEnclosedObject[capella.ExecutionPayload]
   GetValidatorsActivityResponse* = DataEnclosedObject[seq[RestActivityItem]]
   GetValidatorsLivenessResponse* = DataEnclosedObject[seq[RestLivenessItem]]
 
diff --git a/beacon_chain/spec/mev/capella_mev.nim b/beacon_chain/spec/mev/capella_mev.nim
new file mode 100644
index 000000000..f21b6527e
--- /dev/null
+++ b/beacon_chain/spec/mev/capella_mev.nim
@@ -0,0 +1,79 @@
+# beacon_chain
+# Copyright (c) 2023 Status Research & Development GmbH
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+import ".."/datatypes/[altair, capella]
+from stew/byteutils import to0xHex
+
+{.push raises: [].}
+
+type
+  # https://github.com/jimmygchen/builder-specs/blob/0e15394bc239d3fee1ba9e42f4ce67ff6565537b/specs/builder.md#builderbid-1
+  BuilderBid* = object
+    header*: capella.ExecutionPayloadHeader # [Modified in Capella]
+    value*: UInt256
+    pubkey*: ValidatorPubKey
+
+  # https://github.com/jimmygchen/builder-specs/blob/0e15394bc239d3fee1ba9e42f4ce67ff6565537b/specs/builder.md#signedbuilderbid-1
+  SignedBuilderBid* = object
+    message*: BuilderBid # [Modified in Capella]
+    signature*: ValidatorSig
+
+  # https://github.com/jimmygchen/builder-specs/blob/0e15394bc239d3fee1ba9e42f4ce67ff6565537b/specs/builder.md#blindedbeaconblockbody-1
+  BlindedBeaconBlockBody = object
+    randao_reveal*: ValidatorSig
+    eth1_data*: Eth1Data
+    graffiti*: GraffitiBytes
+    proposer_slashings*: List[ProposerSlashing, Limit MAX_PROPOSER_SLASHINGS]
+    attester_slashings*: List[AttesterSlashing, Limit MAX_ATTESTER_SLASHINGS]
+    attestations*: List[Attestation, Limit MAX_ATTESTATIONS]
+    deposits*: List[Deposit, Limit MAX_DEPOSITS]
+    voluntary_exits*: List[SignedVoluntaryExit, Limit MAX_VOLUNTARY_EXITS]
+    sync_aggregate*: SyncAggregate
+    execution_payload_header*:
+      capella.ExecutionPayloadHeader # [Modified in Capella]
+    bls_to_execution_changes*:
+      List[SignedBLSToExecutionChange,
+        Limit MAX_BLS_TO_EXECUTION_CHANGES]  # [New in Capella]
+
+  # https://github.com/jimmygchen/builder-specs/blob/0e15394bc239d3fee1ba9e42f4ce67ff6565537b/specs/builder.md#blindedbeaconblock-1
+  BlindedBeaconBlock* = object
+    slot*: Slot
+    proposer_index*: uint64
+    parent_root*: Eth2Digest
+    state_root*: Eth2Digest
+    body*: BlindedBeaconBlockBody # [Modified in Capella]
+
+  # https://github.com/jimmygchen/builder-specs/blob/0e15394bc239d3fee1ba9e42f4ce67ff6565537b/specs/builder.md#signedblindedbeaconblock-1
+  SignedBlindedBeaconBlock* = object
+    message*: BlindedBeaconBlock
+    signature*: ValidatorSig
+
+func shortLog*(v: BlindedBeaconBlock): auto =
+  (
+    slot: shortLog(v.slot),
+    proposer_index: v.proposer_index,
+    parent_root: shortLog(v.parent_root),
+    state_root: shortLog(v.state_root),
+    eth1data: v.body.eth1_data,
+    graffiti: $v.body.graffiti,
+    proposer_slashings_len: v.body.proposer_slashings.len(),
+    attester_slashings_len: v.body.attester_slashings.len(),
+    attestations_len: v.body.attestations.len(),
+    deposits_len: v.body.deposits.len(),
+    voluntary_exits_len: v.body.voluntary_exits.len(),
+    sync_committee_participants: v.body.sync_aggregate.num_active_participants,
+    block_number: v.body.execution_payload_header.block_number,
+    # TODO checksum hex? shortlog?
+    fee_recipient: to0xHex(v.body.execution_payload_header.fee_recipient.data),
+    bls_to_execution_changes_len: v.body.bls_to_execution_changes.len()
+  )
+
+func shortLog*(v: SignedBlindedBeaconBlock): auto =
+  (
+    blck: shortLog(v.message),
+    signature: shortLog(v.signature)
+  )
diff --git a/beacon_chain/spec/mev/rest_bellatrix_mev_calls.nim b/beacon_chain/spec/mev/rest_bellatrix_mev_calls.nim
index eae638843..f609b0a79 100644
--- a/beacon_chain/spec/mev/rest_bellatrix_mev_calls.nim
+++ b/beacon_chain/spec/mev/rest_bellatrix_mev_calls.nim
@@ -27,8 +27,8 @@ proc getHeader*(slot: Slot,
      meth: MethodGet, connection: {Dedicated, Close}.}
   ## https://github.com/ethereum/builder-specs/blob/v0.2.0/apis/builder/header.yaml
 
-proc submitBlindedBlock*(body: SignedBlindedBeaconBlock
-                        ): RestResponse[SubmitBlindedBlockResponse] {.
+proc submitBlindedBlock*(body: bellatrix_mev.SignedBlindedBeaconBlock
+                        ): RestResponse[SubmitBlindedBlockResponseBellatrix] {.
      rest, endpoint: "/eth/v1/builder/blinded_blocks",
      meth: MethodPost, connection: {Dedicated, Close}.}
   ## https://github.com/ethereum/builder-specs/blob/v0.2.0/apis/builder/blinded_blocks.yaml
diff --git a/beacon_chain/spec/mev/rest_capella_mev_calls.nim b/beacon_chain/spec/mev/rest_capella_mev_calls.nim
new file mode 100644
index 000000000..0b9c8c944
--- /dev/null
+++ b/beacon_chain/spec/mev/rest_capella_mev_calls.nim
@@ -0,0 +1,28 @@
+# Copyright (c) 2023 Status Research & Development GmbH
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+{.push raises: [].}
+
+import
+  chronos, presto/client,
+  ".."/eth2_apis/[rest_types, eth2_rest_serialization]
+
+export chronos, client, rest_types, eth2_rest_serialization
+
+# TODO
+#proc getHeader*(slot: Slot,
+#                parent_hash: Eth2Digest,
+#                pubkey: ValidatorPubKey
+#               ): RestResponse[GetHeaderResponse] {.
+#     rest, endpoint: "/eth/v1/builder/header/{slot}/{parent_hash}/{pubkey}",
+#     meth: MethodGet, connection: {Dedicated, Close}.}
+#  ## https://github.com/jimmygchen/builder-specs/blob/0e15394bc239d3fee1ba9e42f4ce67ff6565537b/apis/builder/header.yaml
+
+proc submitBlindedBlock*(body: capella_mev.SignedBlindedBeaconBlock
+                        ): RestResponse[SubmitBlindedBlockResponseCapella] {.
+     rest, endpoint: "/eth/v1/builder/blinded_blocks",
+     meth: MethodPost, connection: {Dedicated, Close}.}
+  ## https://github.com/jimmygchen/builder-specs/blob/0e15394bc239d3fee1ba9e42f4ce67ff6565537b/apis/builder/blinded_blocks.yaml
diff --git a/beacon_chain/validators/message_router_mev.nim b/beacon_chain/validators/message_router_mev.nim
index a6492b225..b39b9792b 100644
--- a/beacon_chain/validators/message_router_mev.nim
+++ b/beacon_chain/validators/message_router_mev.nim
@@ -14,6 +14,7 @@ import ../beacon_node
 from eth/async_utils import awaitWithTimeout
 from ../spec/datatypes/bellatrix import SignedBeaconBlock
 from ../spec/mev/rest_bellatrix_mev_calls import submitBlindedBlock
+from ../spec/mev/rest_capella_mev_calls import submitBlindedBlock
 
 const
   BUILDER_BLOCK_SUBMISSION_DELAY_TOLERANCE = 4.seconds
@@ -41,7 +42,7 @@ macro copyFields*(
         newDotExpr(dst, ident(name)), newDotExpr(src, ident(name)))
 
 proc unblindAndRouteBlockMEV*(
-    node: BeaconNode, blindedBlock: SignedBlindedBeaconBlock):
+    node: BeaconNode, blindedBlock: bellatrix_mev.SignedBlindedBeaconBlock):
     Future[Result[Opt[BlockRef], string]] {.async.} =
   # By time submitBlindedBlock is called, must already have done slashing
   # protection check
diff --git a/beacon_chain/validators/validator_duties.nim b/beacon_chain/validators/validator_duties.nim
index b850e8cda..d4ef279b8 100644
--- a/beacon_chain/validators/validator_duties.nim
+++ b/beacon_chain/validators/validator_duties.nim
@@ -38,7 +38,7 @@ import
   ../gossip_processing/block_processor,
   ".."/[conf, beacon_clock, beacon_node],
   "."/[slashing_protection, validator_pool, keystore_management],
-  ".."/spec/mev/rest_bellatrix_mev_calls
+  ".."/spec/mev/[rest_bellatrix_mev_calls, rest_capella_mev_calls]
 
 from eth/async_utils import awaitWithTimeout
 
@@ -86,7 +86,7 @@ logScope: topics = "beacval"
 
 type
   ForkedBlockResult* = Result[ForkedBeaconBlock, string]
-  BlindedBlockResult* = Result[BlindedBeaconBlock, string]
+  BlindedBlockResult* = Result[bellatrix_mev.BlindedBeaconBlock, string]
 
   SyncStatus* {.pure.} = enum
     synced
@@ -749,11 +749,12 @@ proc proposeBlockMEV(
 
   # This is only substantively asynchronous with a remote key signer
   let blindedBlock = awaitWithTimeout(
-      getBlindedBeaconBlock[SignedBlindedBeaconBlock](
+      getBlindedBeaconBlock[bellatrix_mev.SignedBlindedBeaconBlock](
         node, slot, validator, validator_index, forkedBlck,
         executionPayloadHeader),
       500.milliseconds):
-    Result[SignedBlindedBeaconBlock, string].err "getBlindedBlock timed out"
+    Result[bellatrix_mev.SignedBlindedBeaconBlock, string].err(
+      "getBlindedBlock timed out")
 
   if blindedBlock.isErr:
     info "proposeBlockMEV: getBlindedBeaconBlock failed",
@@ -815,7 +816,7 @@ proc makeBlindedBeaconBlockForHeadAndSlot*(
     return err("Unable to create blinded block")
 
   let (executionPayloadHeader, forkedBlck) = blindedBlockParts.get
-  return ok constructPlainBlindedBlock[BlindedBeaconBlock](
+  return ok constructPlainBlindedBlock[bellatrix_mev.BlindedBeaconBlock](
     forkedBlck, executionPayloadHeader)
 
 from ../spec/datatypes/eip4844 import shortLog
diff --git a/beacon_chain/validators/validator_pool.nim b/beacon_chain/validators/validator_pool.nim
index a44b5e502..200d8d322 100644
--- a/beacon_chain/validators/validator_pool.nim
+++ b/beacon_chain/validators/validator_pool.nim
@@ -355,7 +355,7 @@ proc getBlockSignature*(v: AttachedValidator, fork: Fork,
                         genesis_validators_root: Eth2Digest, slot: Slot,
                         block_root: Eth2Digest,
                         blck: ForkedBeaconBlock | ForkedBlindedBeaconBlock |
-                              BlindedBeaconBlock
+                              bellatrix_mev.BlindedBeaconBlock
                        ): Future[SignatureResult] {.async.} =
   return
     case v.kind