diff --git a/lib/selectors/thread-selectors.js b/lib/selectors/thread-selectors.js
--- a/lib/selectors/thread-selectors.js
+++ b/lib/selectors/thread-selectors.js
@@ -536,6 +536,62 @@
   baseThreadInfosSelectorForThreadType,
 );
 
+const baseThreadMembersSelectorForThread: (
+  threadID: string,
+) => (
+  BaseAppState<>,
+) => $ReadOnlyMap<string, $ReadOnlyArray<RelativeMemberInfo>> = (
+  threadID: string,
+) =>
+  createSelector(
+    threadInfoSelector,
+    (threadInfos: {
+      +[id: string]: ThreadInfo,
+    }): $ReadOnlyMap<string, $ReadOnlyArray<RelativeMemberInfo>> => {
+      const selectedThreadInfo = threadInfos[threadID];
+      const { community } = selectedThreadInfo;
+
+      const communityThreadInfo = community ? threadInfos[community] : null;
+      const topMostThreadInfo =
+        communityThreadInfo && communityThreadInfo.type !== threadTypes.GENESIS
+          ? communityThreadInfo
+          : selectedThreadInfo;
+
+      const { members, roles } = topMostThreadInfo;
+
+      const roleMap = new Map<string, $ReadOnlyArray<RelativeMemberInfo>>();
+
+      for (const role in roles) {
+        roleMap.set(role, []);
+      }
+
+      for (const member of members) {
+        const memberRole = member.role;
+        if (!memberRole) {
+          continue;
+        }
+
+        const memberList = roleMap.get(memberRole);
+        if (!memberList) {
+          continue;
+        }
+
+        const newMemberList = [...memberList, member];
+        roleMap.set(memberRole, newMemberList);
+      }
+
+      return roleMap;
+    },
+  );
+
+const threadMembersSelectorForThread: (
+  threadID: string,
+) => (
+  state: BaseAppState<>,
+) => $ReadOnlyMap<string, $ReadOnlyArray<RelativeMemberInfo>> = _memoize(
+  baseThreadMembersSelectorForThread,
+);
+
 export {
   ancestorThreadInfos,
   threadInfoSelector,
@@ -557,4 +613,5 @@
   pendingToRealizedThreadIDsSelector,
   savedEmojiAvatarSelectorForThread,
   threadInfosSelectorForThreadType,
+  threadMembersSelectorForThread,
 };