diff --git a/web/chat/thread-menu.react.js b/web/chat/thread-menu.react.js
--- a/web/chat/thread-menu.react.js
+++ b/web/chat/thread-menu.react.js
@@ -6,7 +6,10 @@
 import SWMansionIcon from 'lib/components/swmansion-icon.react.js';
 import { usePromoteSidebar } from 'lib/hooks/promote-sidebar.react.js';
 import { useLeaveThread } from 'lib/hooks/thread-hooks.js';
-import { childThreadInfos } from 'lib/selectors/thread-selectors.js';
+import {
+  childThreadInfos,
+  otherUsersButNoOtherAdmins,
+} from 'lib/selectors/thread-selectors.js';
 import {
   threadIsChannel,
   useThreadHasPermission,
@@ -208,6 +211,9 @@
     popModal();
   }, [leaveThread, popModal, threadInfo]);
 
+  const otherUsersButNoOtherAdminsValue = useSelector(
+    otherUsersButNoOtherAdmins(threadInfo.id),
+  );
   const onClickLeaveThread = React.useCallback(
     () =>
       pushModal(
@@ -215,9 +221,16 @@
           threadInfo={threadInfo}
           onClose={popModal}
           onConfirm={onConfirmLeaveThread}
+          otherUsersButNoOtherAdmins={otherUsersButNoOtherAdminsValue}
         />,
       ),
-    [popModal, onConfirmLeaveThread, pushModal, threadInfo],
+    [
+      pushModal,
+      threadInfo,
+      popModal,
+      onConfirmLeaveThread,
+      otherUsersButNoOtherAdminsValue,
+    ],
   );
 
   const canLeaveThread = useThreadHasPermission(
diff --git a/web/modals/threads/confirm-leave-thread-modal.react.js b/web/modals/threads/confirm-leave-thread-modal.react.js
--- a/web/modals/threads/confirm-leave-thread-modal.react.js
+++ b/web/modals/threads/confirm-leave-thread-modal.react.js
@@ -13,9 +13,10 @@
   +threadInfo: ThreadInfo,
   +onClose: () => void,
   +onConfirm: () => void,
+  +otherUsersButNoOtherAdmins: boolean,
 };
 function ConfirmLeaveThreadModal(props: Props): React.Node {
-  const { threadInfo, onClose, onConfirm } = props;
+  const { threadInfo, onClose, onConfirm, otherUsersButNoOtherAdmins } = props;
   const { uiName } = useResolvedThreadInfo(threadInfo);
 
   const primaryButton = React.useMemo(
@@ -41,6 +42,22 @@
     [onClose],
   );
 
+  if (otherUsersButNoOtherAdmins) {
+    return (
+      <Modal
+        size="fit-content"
+        name="Need another admin"
+        icon="warning-circle"
+        withCloseButton={true}
+        onClose={onClose}
+      >
+        <div className={css.container}>
+          Make somebody else an admin before you leave!
+        </div>
+      </Modal>
+    );
+  }
+
   return (
     <Modal
       size="fit-content"