diff --git a/web/modals/threads/members/add-members-modal.react.js b/web/modals/threads/members/add-members-modal.react.js
index 8bad2b5fc..3a76f1550 100644
--- a/web/modals/threads/members/add-members-modal.react.js
+++ b/web/modals/threads/members/add-members-modal.react.js
@@ -1,139 +1,167 @@
 // @flow
 
 import * as React from 'react';
 
+import {
+  changeThreadSettingsActionTypes,
+  changeThreadSettings,
+} from 'lib/actions/thread-actions';
 import { threadInfoSelector } from 'lib/selectors/thread-selectors';
 import {
   userSearchIndexForPotentialMembers,
   userInfoSelectorForPotentialMembers,
 } from 'lib/selectors/user-selectors';
 import { getPotentialMemberItems } from 'lib/shared/search-utils';
 import { threadActualMembers } from 'lib/shared/thread-utils';
+import {
+  useDispatchActionPromise,
+  useServerCall,
+} from 'lib/utils/action-utils';
 
 import Button from '../../../components/button.react';
 import { useSelector } from '../../../redux/redux-utils';
 import SearchModal from '../../search-modal.react';
 import AddMembersList from './add-members-list.react';
 import css from './members-modal.css';
 
 type ContentProps = {
   +searchText: string,
   +threadID: string,
   +onClose: () => void,
 };
 
 function AddMembersModalContent(props: ContentProps): React.Node {
   const { searchText, threadID, onClose } = props;
 
   const [pendingUsersToAdd, setPendingUsersToAdd] = React.useState<
     $ReadOnlySet<string>,
   >(new Set());
 
   const threadInfo = useSelector(state => threadInfoSelector(state)[threadID]);
   const { parentThreadID, community } = threadInfo;
   const parentThreadInfo = useSelector(state =>
     parentThreadID ? threadInfoSelector(state)[parentThreadID] : null,
   );
   const communityThreadInfo = useSelector(state =>
     community ? threadInfoSelector(state)[community] : null,
   );
   const otherUserInfos = useSelector(userInfoSelectorForPotentialMembers);
   const userSearchIndex = useSelector(userSearchIndexForPotentialMembers);
   const excludeUserIDs = React.useMemo(
     () => threadActualMembers(threadInfo.members),
     [threadInfo.members],
   );
 
   const userSearchResults = React.useMemo(
     () =>
       getPotentialMemberItems(
         searchText,
         otherUserInfos,
         userSearchIndex,
         excludeUserIDs,
         parentThreadInfo,
         communityThreadInfo,
         threadInfo.type,
       ),
     [
       communityThreadInfo,
       excludeUserIDs,
       otherUserInfos,
       parentThreadInfo,
       searchText,
       threadInfo.type,
       userSearchIndex,
     ],
   );
 
   const onSwitchUser = React.useCallback(
     userID =>
       setPendingUsersToAdd(users => {
         const newUsers = new Set(users);
         if (newUsers.has(userID)) {
           newUsers.delete(userID);
         } else {
           newUsers.add(userID);
         }
         return newUsers;
       }),
     [],
   );
 
+  const dispatchActionPromise = useDispatchActionPromise();
+  const callChangeThreadSettings = useServerCall(changeThreadSettings);
+
+  const addUsers = React.useCallback(() => {
+    dispatchActionPromise(
+      changeThreadSettingsActionTypes,
+      callChangeThreadSettings({
+        threadID,
+        changes: { newMemberIDs: Array.from(pendingUsersToAdd) },
+      }),
+    );
+    onClose();
+  }, [
+    callChangeThreadSettings,
+    dispatchActionPromise,
+    onClose,
+    pendingUsersToAdd,
+    threadID,
+  ]);
+
   return (
     <div className={css.addMembersContent}>
       <div className={css.addMembersListContainer}>
         <AddMembersList
           userListItems={userSearchResults}
           switchUser={onSwitchUser}
           pendingUsersToAdd={pendingUsersToAdd}
         />
       </div>
       <div className={css.addMembersFooter}>
         <Button onClick={onClose} variant="secondary">
           Cancel
         </Button>
         <Button
           disabled={!pendingUsersToAdd.size}
           variant="primary"
-          onClick={() => {}}
+          onClick={addUsers}
         >
           Add selected members
         </Button>
       </div>
     </div>
   );
 }
 
 type Props = {
   +threadID: string,
   +onClose: () => void,
 };
 
 function AddMembersModal(props: Props): React.Node {
   const { threadID, onClose } = props;
 
   const addMembersModalContent = React.useCallback(
     (searchText: string) => (
       <AddMembersModalContent
         searchText={searchText}
         threadID={threadID}
         onClose={onClose}
       />
     ),
     [onClose, threadID],
   );
 
   return (
     <SearchModal
       name="Add members"
       searchPlaceholder="Search members"
       onClose={onClose}
       size="fit-content"
     >
       {addMembersModalContent}
     </SearchModal>
   );
 }
 
 export default AddMembersModal;