diff --git a/lib/hooks/thread-hooks.js b/lib/hooks/thread-hooks.js
--- a/lib/hooks/thread-hooks.js
+++ b/lib/hooks/thread-hooks.js
@@ -5,6 +5,7 @@
 import uuid from 'uuid';
 
 import { useChatMentionContext } from './chat-mention-hooks.js';
+import { useGetCommFCUsersForFIDs } from './user-identities-hooks.js';
 import genesis from '../facts/genesis.js';
 import { extractKeyserverIDFromID } from '../keyserver-conn/keyserver-call-utils.js';
 import { useKeyserverCall } from '../keyserver-conn/keyserver-call.js';
@@ -51,7 +52,7 @@
 } from '../types/thread-types.js';
 import { values } from '../utils/objects.js';
 import { useDispatchActionPromise } from '../utils/redux-promise-utils.js';
-import { useSelector } from '../utils/redux-utils.js';
+import { useSelector, useDispatch } from '../utils/redux-utils.js';
 
 function useChildThreadInfosMap(): {
   +[id: string]: $ReadOnlyArray<ResolvedThreadInfo>,
@@ -238,6 +239,8 @@
     useUpdateFarcasterGroupNameAndDescription();
   const fetchFarcasterConversation = useFetchFarcasterConversation();
   const fetchFarcasterMessages = useFetchFarcasterMessages();
+  const fetchUsersByFIDs = useGetCommFCUsersForFIDs();
+  const dispatch = useDispatch();
 
   return React.useCallback(
     async (input: UseChangeThreadSettingsInput) =>
@@ -249,6 +252,8 @@
           updateFarcasterGroupNameAndDescription,
           fetchFarcasterConversation,
           fetchFarcasterMessages,
+          fetchUsersByFIDs,
+          dispatch,
         },
       ),
     [
@@ -258,6 +263,8 @@
       updateFarcasterGroupNameAndDescription,
       viewerID,
       fetchFarcasterMessages,
+      fetchUsersByFIDs,
+      dispatch,
     ],
   );
 }
diff --git a/lib/shared/farcaster/farcaster-hooks.js b/lib/shared/farcaster/farcaster-hooks.js
--- a/lib/shared/farcaster/farcaster-hooks.js
+++ b/lib/shared/farcaster/farcaster-hooks.js
@@ -11,14 +11,21 @@
   useSendFarcasterTextMessage,
 } from './farcaster-api.js';
 import type { FarcasterConversation } from './farcaster-conversation-types.js';
-import type { FarcasterMessage } from './farcaster-messages-types';
+import {
+  farcasterMessageValidator,
+  type FarcasterMessage,
+} from './farcaster-messages-types.js';
+import { processNewUserIDsActionType } from '../../actions/user-actions.js';
+import { useGetCommFCUsersForFIDs } from '../../hooks/user-identities-hooks.js';
 import { messageTruncationStatus } from '../../types/message-types.js';
 import { updateTypes } from '../../types/update-types-enum.js';
+import { extractFarcasterIDsFromPayload } from '../../utils/conversion-utils.js';
 import { convertFarcasterMessageToCommMessages } from '../../utils/convert-farcaster-message-to-comm-messages.js';
 import { createFarcasterRawThreadInfo } from '../../utils/create-farcaster-raw-thread-info.js';
 import { useSetFarcasterDCsLoaded } from '../../utils/farcaster-utils.js';
 import { useDispatch } from '../../utils/redux-utils.js';
 import { useSendDMOperationUtils } from '../dm-ops/dm-op-utils.js';
+import { userIDFromFID } from '../id-utils.js';
 
 async function processInBatches<T, R>(
   items: $ReadOnlyArray<T>,
@@ -86,6 +93,7 @@
   messagesNumberLimit?: number,
 ) => Promise<void> {
   const fetchFarcasterMessages = useFetchFarcasterMessages();
+  const fetchUsersByFIDs = useGetCommFCUsersForFIDs();
   const dispatch = useDispatch();
 
   return React.useCallback(
@@ -117,10 +125,29 @@
 
           if (messagesResult) {
             const farcasterMessages = messagesResult.result.messages;
-            const rawMessageInfos = farcasterMessages.flatMap(
-              convertFarcasterMessageToCommMessages,
+
+            const userFIDs = farcasterMessages.flatMap(message =>
+              extractFarcasterIDsFromPayload(
+                farcasterMessageValidator,
+                message,
+              ),
+            );
+            const fcUserInfos = await fetchUsersByFIDs(userFIDs);
+
+            const rawMessageInfos = farcasterMessages.flatMap(message =>
+              convertFarcasterMessageToCommMessages(message, fcUserInfos),
             );
 
+            if (fcUserInfos.size > 0) {
+              const newUserIDs = Array.from(fcUserInfos.entries()).map(
+                ([fid, user]) => user?.userID ?? userIDFromFID(fid),
+              );
+              dispatch({
+                type: processNewUserIDsActionType,
+                payload: { userIDs: newUserIDs },
+              });
+            }
+
             if (rawMessageInfos.length > 0) {
               const payload =
                 totalMessagesFetched === 0
@@ -146,7 +173,7 @@
         console.error(`Failed fetching messages for ${conversationID}:`, e);
       }
     },
-    [fetchFarcasterMessages, dispatch],
+    [fetchFarcasterMessages, fetchUsersByFIDs, dispatch],
   );
 }
 
diff --git a/lib/shared/id-utils.js b/lib/shared/id-utils.js
--- a/lib/shared/id-utils.js
+++ b/lib/shared/id-utils.js
@@ -148,6 +148,20 @@
   return threadID.replace(farcasterIDPrefix, '');
 }
 
+const farcasterUserIDPrefix = 'FID#';
+
+function userIDFromFID(farcasterID: string): string {
+  return `${farcasterUserIDPrefix}${farcasterID}`;
+}
+
+function extractFIDFromUserID(userID: string): ?string {
+  if (!userID.includes(farcasterUserIDPrefix)) {
+    return null;
+  }
+
+  return userID.replace(farcasterUserIDPrefix, '');
+}
+
 export {
   getNextLocalID,
   getOldestNonLocalMessageID,
@@ -162,4 +176,6 @@
   farcasterIDPrefix,
   farcasterThreadIDFromConversationID,
   conversationIDFromFarcasterThreadID,
+  userIDFromFID,
+  extractFIDFromUserID,
 };
diff --git a/lib/shared/threads/protocols/farcaster-thread-protocol.js b/lib/shared/threads/protocols/farcaster-thread-protocol.js
--- a/lib/shared/threads/protocols/farcaster-thread-protocol.js
+++ b/lib/shared/threads/protocols/farcaster-thread-protocol.js
@@ -37,10 +37,15 @@
 } from '../../../types/thread-types.js';
 import { updateTypes } from '../../../types/update-types-enum.js';
 import { type ThreadUpdateInfo } from '../../../types/update-types.js';
+import { extractFarcasterIDsFromPayload } from '../../../utils/conversion-utils.js';
 import { convertFarcasterMessageToCommMessages } from '../../../utils/convert-farcaster-message-to-comm-messages.js';
 import { createFarcasterRawThreadInfo } from '../../../utils/create-farcaster-raw-thread-info.js';
 import { farcasterThreadIDRegExp } from '../../../utils/validation-utils.js';
-import { conversationIDFromFarcasterThreadID } from '../../id-utils.js';
+import { farcasterMessageValidator } from '../../farcaster/farcaster-messages-types.js';
+import {
+  conversationIDFromFarcasterThreadID,
+  userIDFromFID,
+} from '../../id-utils.js';
 import { messageNotifyTypes } from '../../messages/message-spec.js';
 import { getSingleOtherUser } from '../../thread-utils.js';
 import type {
@@ -124,6 +129,8 @@
       updateFarcasterGroupNameAndDescription,
       fetchFarcasterConversation,
       fetchFarcasterMessages,
+      fetchUsersByFIDs,
+      dispatch,
     } = utils;
     invariant(
       !changes.color,
@@ -178,11 +185,29 @@
     const messagesResponse = await fetchFarcasterMessages({
       conversationId,
     });
-    const newMessageInfos = messagesResponse.result.messages.flatMap(
-      farcasterMessage =>
-        convertFarcasterMessageToCommMessages(farcasterMessage),
+    const farcasterMessages = messagesResponse.result.messages;
+    const userFIDs = farcasterMessages.flatMap(message =>
+      extractFarcasterIDsFromPayload(farcasterMessageValidator, message),
+    );
+
+    const fcUserInfos = await fetchUsersByFIDs(userFIDs);
+
+    const newMessageInfos = farcasterMessages.flatMap(farcasterMessage =>
+      convertFarcasterMessageToCommMessages(farcasterMessage, fcUserInfos),
     );
 
+    if (fcUserInfos.size > 0) {
+      const newUserIDs = Array.from(fcUserInfos.entries()).map(
+        ([fid, user]) => user?.userID ?? userIDFromFID(fid),
+      );
+      dispatch({
+        // TODO: importing processNewUserIDsActionType causes circular
+        // dependencies that are hard to resolve
+        type: 'PROCESS_NEW_USER_IDS',
+        payload: { userIDs: newUserIDs },
+      });
+    }
+
     return ({
       threadID: threadInfo.id,
       updatesResult: { newUpdates: [update] },
diff --git a/lib/shared/threads/thread-spec.js b/lib/shared/threads/thread-spec.js
--- a/lib/shared/threads/thread-spec.js
+++ b/lib/shared/threads/thread-spec.js
@@ -23,6 +23,7 @@
   LeaveThreadInput,
   LeaveThreadResult,
 } from '../../hooks/thread-hooks.js';
+import type { GetCommFCUsersForFIDs } from '../../hooks/user-identities-hooks.js';
 import type { RolePermissionBlobs } from '../../permissions/thread-permissions.js';
 import type { ProcessOutboundP2PMessagesResult } from '../../tunnelbroker/peer-to-peer-context.js';
 import type { TunnelbrokerSocketState } from '../../tunnelbroker/tunnelbroker-context.js';
@@ -162,6 +163,8 @@
   +updateFarcasterGroupNameAndDescription: UpdateFarcasterGroupNameAndDescriptionInput => Promise<void>,
   +fetchFarcasterConversation: FetchFarcasterConversationInput => Promise<FetchFarcasterConversationResult>,
   +fetchFarcasterMessages: FetchFarcasterMessageInput => Promise<FetchFarcasterMessageResult>,
+  +fetchUsersByFIDs: GetCommFCUsersForFIDs,
+  +dispatch: Dispatch,
 };
 
 export type ProtocolCreateEntryInput = {
diff --git a/lib/utils/convert-farcaster-message-to-comm-messages.js b/lib/utils/convert-farcaster-message-to-comm-messages.js
--- a/lib/utils/convert-farcaster-message-to-comm-messages.js
+++ b/lib/utils/convert-farcaster-message-to-comm-messages.js
@@ -1,16 +1,24 @@
 // @flow
 import uuid from 'uuid';
 
+import type { FCUserInfos } from '../hooks/user-identities-hooks.js';
 import type { FarcasterMessage } from '../shared/farcaster/farcaster-messages-types.js';
-import { farcasterThreadIDFromConversationID } from '../shared/id-utils.js';
+import {
+  farcasterThreadIDFromConversationID,
+  userIDFromFID,
+} from '../shared/id-utils.js';
 import type { Media } from '../types/media-types.js';
 import { messageTypes } from '../types/message-types-enum.js';
 import type { RawMessageInfo } from '../types/message-types.js';
 
 function convertFarcasterMessageToCommMessages(
   farcasterMessage: FarcasterMessage,
+  fcUserInfos?: FCUserInfos,
 ): $ReadOnlyArray<RawMessageInfo> {
-  const creatorID = `${farcasterMessage.senderFid}`;
+  const senderFid = farcasterMessage.senderFid.toString();
+  const creatorID =
+    fcUserInfos?.get(senderFid)?.userID ?? userIDFromFID(senderFid);
+
   const threadID = farcasterThreadIDFromConversationID(
     farcasterMessage.conversationId,
   );
@@ -18,7 +26,10 @@
     farcasterMessage.type === 'group_membership_addition' &&
     farcasterMessage.actionTargetUserContext?.fid
   ) {
-    const addedUser = `${farcasterMessage.actionTargetUserContext.fid}`;
+    const addedUserFID =
+      farcasterMessage.actionTargetUserContext.fid.toString();
+    const addedUser =
+      fcUserInfos?.get(addedUserFID)?.userID ?? userIDFromFID(addedUserFID);
     return [
       {
         id: farcasterMessage.messageId,