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
@@ -1,11 +1,24 @@
 // @flow
 
+import invariant from 'invariant';
 import * as React from 'react';
+import uuid from 'uuid';
 
 import { useChatMentionContext } from './chat-mention-hooks.js';
 import genesis from '../facts/genesis.js';
 import { childThreadInfos } from '../selectors/thread-selectors.js';
+import {
+  type OutboundDMOperationSpecification,
+  dmOperationSpecificationTypes,
+} from '../shared/dm-ops/dm-op-utils.js';
+import { useProcessAndSendDMOperation } from '../shared/dm-ops/process-dm-ops.js';
+import type {
+  DMCreateSidebarOperation,
+  DMCreateThreadOperation,
+} from '../types/dm-ops';
 import type { ResolvedThreadInfo } from '../types/minimally-encoded-thread-permissions-types.js';
+import { threadTypes } from '../types/thread-types-enum.js';
+import type { NewThickThreadRequest } from '../types/thread-types.js';
 import { useSelector } from '../utils/redux-utils.js';
 
 function useChildThreadInfosMap(): {
@@ -46,4 +59,68 @@
   ]);
 }
 
-export { useChildThreadInfosMap };
+function useNewThickThread(): (
+  input: NewThickThreadRequest,
+) => Promise<string> {
+  const processAndSendDMOperation = useProcessAndSendDMOperation();
+  const viewerID = useSelector(
+    state => state.currentUserInfo && state.currentUserInfo.id,
+  );
+
+  return React.useCallback(
+    async (input: NewThickThreadRequest) => {
+      invariant(viewerID, 'viewerID must be defined');
+      const threadID = input.id ?? uuid.v4();
+
+      let op;
+      if (input.type === threadTypes.THICK_SIDEBAR) {
+        const { parentThreadID, sourceMessageID, initialMemberIDs } = input;
+        invariant(
+          parentThreadID,
+          'parentThreadID has to be defined for thick sidebar',
+        );
+        const sidebarOP: DMCreateSidebarOperation = {
+          creatorID: viewerID,
+          memberIDs: initialMemberIDs ?? [],
+          newCreateSidebarMessageID: uuid.v4(),
+          newSidebarSourceMessageID: uuid.v4(),
+          parentThreadID: parentThreadID,
+          roleID: uuid.v4(),
+          sourceMessageID: sourceMessageID,
+          threadID,
+          time: Date.now(),
+          type: 'create_sidebar',
+        };
+        op = sidebarOP;
+      } else {
+        const { type, initialMemberIDs } = input;
+
+        const threadOP: DMCreateThreadOperation = {
+          creatorID: viewerID,
+          memberIDs: initialMemberIDs ?? [],
+          newMessageID: uuid.v4(),
+          roleID: uuid.v4(),
+          threadID,
+          threadType: type,
+          time: Date.now(),
+          type: 'create_thread',
+        };
+        op = threadOP;
+      }
+      const userIDs = [...(input.initialMemberIDs ?? []), viewerID];
+      const opSpecification: OutboundDMOperationSpecification = {
+        type: dmOperationSpecificationTypes.OUTBOUND,
+        op,
+        recipients: {
+          type: 'some_users',
+          userIDs,
+        },
+      };
+      await processAndSendDMOperation(opSpecification);
+      return threadID;
+    },
+    [processAndSendDMOperation, viewerID],
+  );
+}
+
+export { useChildThreadInfosMap, useNewThickThread };
diff --git a/lib/types/thread-types.js b/lib/types/thread-types.js
--- a/lib/types/thread-types.js
+++ b/lib/types/thread-types.js
@@ -357,6 +357,18 @@
   +calendarQuery?: ?CalendarQuery,
 }>;
 
+export type NewThickThreadRequest =
+  | $ReadOnly<{
+      +type: 13 | 14 | 15,
+      ...BaseNewThreadRequest,
+    }>
+  | $ReadOnly<{
+      +type: 16,
+      +sourceMessageID: string,
+      ...BaseNewThreadRequest,
+      +parentThreadID: string,
+    }>;
+
 export type NewThreadResponse = {
   +updatesResult: {
     +newUpdates: $ReadOnlyArray<ServerUpdateInfo>,