diff --git a/web/modals/threads/members/change-member-role-modal.css b/web/modals/threads/members/change-member-role-modal.css
index 78daa271b..47802ef7a 100644
--- a/web/modals/threads/members/change-member-role-modal.css
+++ b/web/modals/threads/members/change-member-role-modal.css
@@ -1,50 +1,74 @@
 .roleModalDescription {
   color: var(--change-member-role-modal-description-text);
   padding: 16px 32px 0 32px;
   font-size: medium;
   line-height: 1.5;
 }
 
 .roleModalMember {
   display: flex;
   align-items: center;
   justify-content: center;
   margin-top: 24px;
 }
 
 .roleModalMemberAvatar {
   margin-right: 4px;
 }
 
 .roleModalMemberName {
   margin-left: 4px;
   font-size: large;
   color: var(--change-member-role-modal-generic-text);
 }
 
 .roleModalRoleSelector {
   display: flex;
   justify-content: center;
   flex-direction: column;
   align-items: center;
   padding: 20px 20px 0 20px;
 }
 
 .roleModalActionButtons {
   width: 100%;
   display: flex;
   flex-direction: row;
   justify-content: flex-end;
   align-self: center;
   align-items: stretch;
   margin: 16px 200px 16px 0;
 }
 
 .roleModalSaveButton {
   margin-left: 8px;
   padding: 14px 32px;
 }
 
 .roleModalBackButton {
   padding: 14px 32px;
 }
+
+.roleModalDisabled {
+  color: var(--change-member-role-modal-description-text);
+  background-color: var(--change-member-role-modal-disabled-background);
+  padding: 8px;
+  width: 73%;
+  display: flex;
+  flex-direction: row;
+  justify-content: center;
+  align-items: center;
+  margin: 0 auto;
+  border-radius: 10px;
+  margin-bottom: 20px;
+}
+
+.infoIcon {
+  margin-right: 4px;
+  margin-bottom: 12px;
+}
+
+.infoText {
+  font-size: var(--s-font-14);
+  padding: 4px;
+}
diff --git a/web/modals/threads/members/change-member-role-modal.react.js b/web/modals/threads/members/change-member-role-modal.react.js
index 74bb0079f..637b2b936 100644
--- a/web/modals/threads/members/change-member-role-modal.react.js
+++ b/web/modals/threads/members/change-member-role-modal.react.js
@@ -1,128 +1,163 @@
 // @flow
 
 import invariant from 'invariant';
 import * as React from 'react';
 
 import {
   changeThreadMemberRoles,
   changeThreadMemberRolesActionTypes,
 } from 'lib/actions/thread-actions.js';
 import { useModalContext } from 'lib/components/modal-provider.react.js';
+import SWMansionIcon from 'lib/components/SWMansionIcon.react.js';
+import { otherUsersButNoOtherAdmins } from 'lib/selectors/thread-selectors.js';
+import { roleIsAdminRole } from 'lib/shared/thread-utils.js';
 import type { RelativeMemberInfo, ThreadInfo } from 'lib/types/thread-types';
 import {
   useDispatchActionPromise,
   useServerCall,
 } from 'lib/utils/action-utils.js';
 import { values } from 'lib/utils/objects.js';
 
 import css from './change-member-role-modal.css';
 import UserAvatar from '../../../avatars/user-avatar.react.js';
 import Button, { buttonThemes } from '../../../components/button.react.js';
 import Dropdown from '../../../components/dropdown.react.js';
+import { useSelector } from '../../../redux/redux-utils.js';
 import Modal from '../../modal.react.js';
 import UnsavedChangesModal from '../../unsaved-changes-modal.react.js';
 
 type ChangeMemberRoleModalProps = {
   +memberInfo: RelativeMemberInfo,
   +threadInfo: ThreadInfo,
 };
 
 function ChangeMemberRoleModal(props: ChangeMemberRoleModalProps): React.Node {
   const { memberInfo, threadInfo } = props;
   const { pushModal, popModal } = useModalContext();
   const dispatchActionPromise = useDispatchActionPromise();
   const callChangeThreadMemberRoles = useServerCall(changeThreadMemberRoles);
+  const otherUsersButNoOtherAdminsValue = useSelector(
+    otherUsersButNoOtherAdmins(threadInfo.id),
+  );
 
   const roleOptions = React.useMemo(
     () =>
       values(threadInfo.roles).map(role => ({
         id: role.id,
         name: role.name,
       })),
     [threadInfo.roles],
   );
 
   const initialSelectedRole = memberInfo.role;
   invariant(initialSelectedRole, "Member's role must be defined");
 
   const [selectedRole, setSelectedRole] = React.useState(initialSelectedRole);
 
   const onBackClick = React.useCallback(() => {
     if (selectedRole === initialSelectedRole) {
       popModal();
       return;
     }
 
     pushModal(<UnsavedChangesModal />);
   }, [initialSelectedRole, popModal, pushModal, selectedRole]);
 
+  const disabledRoleChangeMessage = React.useMemo(() => {
+    const memberIsAdmin = roleIsAdminRole(
+      threadInfo.roles[initialSelectedRole],
+    );
+
+    if (!otherUsersButNoOtherAdminsValue || !memberIsAdmin) {
+      return null;
+    }
+
+    return (
+      <>
+        <div className={css.roleModalDisabled}>
+          <SWMansionIcon
+            icon="info-circle"
+            size={36}
+            className={css.infoIcon}
+          />
+          <div className={css.infoText}>
+            There must be at least one admin at any given time in a community.
+          </div>
+        </div>
+      </>
+    );
+  }, [initialSelectedRole, otherUsersButNoOtherAdminsValue, threadInfo.roles]);
+
   const onSave = React.useCallback(() => {
     if (selectedRole === initialSelectedRole) {
       popModal();
       return;
     }
 
     const createChangeThreadMemberRolesPromise = () => {
       return callChangeThreadMemberRoles(
         threadInfo.id,
         [memberInfo.id],
         selectedRole,
       );
     };
 
     dispatchActionPromise(
       changeThreadMemberRolesActionTypes,
       createChangeThreadMemberRolesPromise(),
     );
     popModal();
   }, [
     callChangeThreadMemberRoles,
     dispatchActionPromise,
     initialSelectedRole,
     memberInfo.id,
     popModal,
     selectedRole,
     threadInfo.id,
   ]);
 
   return (
     <Modal name="Change Role" onClose={popModal} size="large">
       <div className={css.roleModalDescription}>
         Members can only be assigned to one role at a time. Changing a
         member&rsquo;s role will replace their previously assigned role.
       </div>
       <div className={css.roleModalMember}>
         <div className={css.roleModalMemberAvatar}>
           <UserAvatar userID={memberInfo.id} size="large" />
         </div>
         <div className={css.roleModalMemberName}>{memberInfo.username}</div>
       </div>
       <div className={css.roleModalRoleSelector}>
         <Dropdown
           options={roleOptions}
           activeSelection={selectedRole}
           setActiveSelection={setSelectedRole}
+          disabled={!!disabledRoleChangeMessage}
         />
       </div>
+      {disabledRoleChangeMessage}
       <div className={css.roleModalActionButtons}>
         <Button
           variant="outline"
           className={css.roleModalBackButton}
           onClick={onBackClick}
         >
           Back
         </Button>
         <Button
           variant="filled"
           className={css.roleModalSaveButton}
           buttonColor={buttonThemes.primary}
           onClick={onSave}
+          disabled={!!disabledRoleChangeMessage}
         >
           Save
         </Button>
       </div>
     </Modal>
   );
 }
 
 export default ChangeMemberRoleModal;
diff --git a/web/theme.css b/web/theme.css
index c4044b640..22531245c 100644
--- a/web/theme.css
+++ b/web/theme.css
@@ -1,239 +1,240 @@
 :root {
   /* Never use color values defined here directly in CSS. Add color variables to "Color Theme" below
 
      The reason we never use color values defined here directly in CSS is
 
       1. It makes changing themes from light / dark / user generated impossible.
       2. Gives the programmer context into the color being used.
       3. If our color system changes it's much easier to change color values in one place.
 
      Add a color value to the theme below, and then use it in your CSS.
      naming convention:
      - bg: background.
      - fg: foreground.
      - color: text-color
    */
   --shades-white-100: #ffffff;
   --shades-white-90: #f5f5f5;
   --shades-white-80: #ebebeb;
   --shades-white-70: #e0e0e0;
   --shades-white-60: #cccccc;
 
   --shades-black-100: #0a0a0a;
   --shades-black-90: #1f1f1f;
   --shades-black-80: #404040;
   --shades-black-70: #666666;
   --shades-black-60: #808080;
 
   --violet-dark-100: #7e57c2;
   --violet-dark-80: #6d49ab;
   --violet-dark-60: #563894;
   --violet-dark-40: #44297a;
   --violet-dark-20: #331f5c;
 
   --violet-light-100: #ae94db;
   --violet-light-80: #b9a4df;
   --violet-light-60: #d3c6ec;
   --violet-light-40: #e8e0f5;
   --violet-light-20: #f3f0fa;
 
   --success-light-10: #d5f6e3;
   --success-light-50: #6cdf9c;
   --success-primary: #00c853;
   --success-dark-50: #029841;
   --success-dark-90: #034920;
 
   --error-light-10: #feebe6;
   --error-light-50: #f9947b;
   --error-primary: #f53100;
   --error-dark-50: #b62602;
   --error-dark-90: #4f1203;
 
   --logo-bg: #111827;
   --spoiler-color: #33332c;
   --loading-foreground: #1b0e38;
 
   --bg: var(--shades-black-100);
   --fg: var(--shades-white-100);
   --color-disabled: var(--shades-black-60);
   --text-input-bg: var(--shades-black-80);
   --text-input-color: var(--shades-white-60);
   --text-input-placeholder: var(--shades-white-60);
   --border: var(--shades-black-80);
   --error: var(--error-primary);
   --success: var(--success-dark-50);
 
   /* Color Theme */
 
   --btn-bg-filled: var(--violet-dark-100);
   --btn-bg-outline: var(--shades-black-90);
   --btn-bg-success: var(--success-dark-50);
   --btn-bg-danger: var(--error-primary);
   --btn-bg-disabled: var(--shades-black-80);
   --btn-disabled-color: var(--shades-black-60);
   --chat-bg: var(--violet-dark-80);
   --chat-confirmation-icon: var(--violet-dark-100);
   --keyserver-selection: var(--violet-dark-60);
   --thread-selection: var(--violet-light-80);
   --thread-hover-bg: var(--shades-black-80);
   --thread-active-bg: var(--shades-black-80);
   --chat-timestamp-color: var(--shades-black-60);
   --tool-tip-bg: var(--shades-black-80);
   --tool-tip-color: var(--shades-white-60);
   --border-color: var(--shades-black-80);
   --calendar-chevron: var(--shades-black-60);
   --calendar-day-bg: var(--shades-black-60);
   --calendar-day-selected-color: var(--violet-dark-80);
   --community-bg: var(--shades-black-90);
   --community-settings-selected: var(--violet-dark-60);
   --unread-bg: var(--error-primary);
   --settings-btn-bg: var(--violet-dark-100);
   --community-creation-btn-bg: var(--shades-black-80);
   --community-creation-ancestry-bg: var(--shades-black-80);
   --community-creation-ancestry-text: var(--shades-black-60);
   --community-creation-form-notice: var(--shades-white-60);
   --community-creation-keyserver-container: var(--shades-black-100);
   --modal-bg: var(--shades-black-90);
   --modal-fg: var(--shades-white-60);
   --join-bg: var(--shades-black-90);
   --help-color: var(--shades-black-60);
   --breadcrumb-color: var(--shades-white-60);
   --breadcrumb-color-unread: var(--shades-white-60);
   --btn-outline-border: var(--shades-black-60);
   --thread-color-read: var(--shades-black-60);
   --thread-preview-secondary: var(--shades-black-70);
   --relationship-button-green: var(--success-dark-50);
   --relationship-button-red: var(--error-primary);
   --relationship-button-text: var(--fg);
   --disconnected-bar-alert-bg: var(--error-dark-50);
   --disconnected-bar-alert-color: var(--shades-white-100);
   --disconnected-bar-connecting-bg: var(--shades-white-70);
   --disconnected-bar-connecting-color: var(--shades-black-100);
   --permission-color: var(--shades-white-60);
   --thread-top-bar-color: var(--shades-white-100);
   --thread-top-bar-menu-color: var(--shades-white-70);
   --thread-ancestor-keyserver-border: var(--shades-black-70);
   --thread-ancestor-color: var(--shades-white-100);
   --thread-ancestor-separator-color: var(--shades-white-60);
   --text-message-default-background: var(--shades-black-80);
   --message-action-tooltip-bg: var(--shades-black-90);
   --message-action-tooltip-bg-light: var(--shades-black-80);
   --menu-bg: var(--shades-black-90);
   --menu-bg-light: var(--shades-black-80);
   --menu-separator-color: var(--shades-black-80);
   --menu-color: var(--shades-black-60);
   --menu-color-light: var(--shades-white-60);
   --menu-color-hover: var(--shades-white-100);
   --menu-color-dangerous: var(--error-primary);
   --menu-color-dangerous-hover: var(--error-light-50);
   --app-list-icon-read-only-color: var(--shades-black-60);
   --app-list-icon-enabled-color: var(--success-primary);
   --app-list-icon-disabled-color: var(--shades-white-80);
   --account-settings-label: var(--shades-black-60);
   --account-button-color: var(--violet-dark-100);
   --chat-thread-list-color-active: var(--shades-white-60);
   --chat-thread-list-menu-color: var(--shades-white-60);
   --chat-thread-list-menu-bg: var(--shades-black-80);
   --chat-thread-list-menu-active-color: var(--shades-white-60);
   --chat-thread-list-menu-active-bg: var(--shades-black-90);
   --search-clear-color: var(--shades-white-100);
   --search-clear-bg: var(--shades-black-70);
   --search-input-color: var(--shades-white-100);
   --search-input-placeholder: var(--shades-black-60);
   --search-icon-color: var(--shades-black-60);
   --tabs-header-active-color: var(--shades-white-100);
   --tabs-header-active-border: var(--violet-light-100);
   --tabs-header-active-background: var(--violet-dark-100);
   --tabs-header-background-color: var(--shades-black-60);
   --tabs-header-background-color-pill: var(--shades-white-60);
   --tabs-header-background-border: var(--shades-black-80);
   --tabs-header-background-color-hover: var(--shades-white-80);
   --tabs-header-background-border-hover: var(--shades-black-70);
   --members-modal-member-text: var(--shades-black-60);
   --members-modal-member-text-hover: var(--shades-white-100);
   --label-default-bg: var(--violet-dark-80);
   --label-default-color: var(--shades-white-80);
   --label-grey-bg: var(--shades-black-80);
   --label-grey-color: var(--shades-white-80);
   --subchannels-modal-color: var(--shades-black-60);
   --subchannels-modal-color-hover: var(--shades-white-100);
   --color-selector-active-bg: var(--shades-black-80);
   --relationship-modal-color: var(--shades-black-60);
   --arrow-extension-color: var(--shades-black-60);
   --modal-close-color: var(--shades-black-60);
   --modal-close-color-hover: var(--shades-white-100);
   --add-members-group-header-color: var(--shades-black-60);
   --add-members-item-color: var(--shades-black-60);
   --add-members-item-color-hover: var(--shades-white-100);
   --add-members-item-disabled-color: var(--shades-black-80);
   --add-members-item-disabled-color-hover: var(--shades-black-60);
   --add-members-remove-pending-color: var(--error-primary);
   --add-members-remove-pending-color-hover: var(--error-light-50);
   --radio-border: var(--shades-black-70);
   --radio-color: var(--shades-white-60);
   --notification-settings-option-selected-bg: var(--shades-black-80);
   --notification-settings-option-title-color: var(--shades-white-90);
   --notification-settings-option-color: var(--shades-white-60);
   --notification-settings-option-invalid-color: var(--shades-black-80);
   --notification-settings-option-invalid-selected-color: var(--shades-black-60);
   --danger-zone-subheading-color: var(--shades-white-60);
   --danger-zone-explanation-color: var(--shades-black-60);
   --thread-creation-search-container-bg: var(--shades-black-90);
   --thread-creation-close-search-color: var(--shades-black-60);
   --thread-creation-search-item-bg-hover: var(--shades-black-80);
   --thread-creation-search-item-info-color: var(--shades-black-60);
   --chat-message-list-active-border: #5989d6;
   --sidebars-modal-color: var(--shades-black-60);
   --sidebars-modal-color-hover: var(--shades-white-100);
   --inline-engagement-bg: var(--shades-black-70);
   --inline-engagement-bg-hover: var(--shades-black-80);
   --inline-engagement-color: var(--fg);
   --compose-subchannel-header-fg: var(--shades-black-60);
   --compose-subchannel-header-bg: var(--shades-black-80);
   --compose-subchannel-label-color: var(--shades-black-60);
   --compose-subchannel-mark-color: var(--violet-light-100);
   --enum-option-icon-color: var(--violet-dark-100);
   --show-password-bg-hover: var(--shades-black-70);
   --typeahead-overlay-light: var(--shades-black-80);
   --typeahead-overlay-dark: var(--shades-black-90);
   --typeahead-overlay-text: var(--shades-white-100);
   --typeahead-overlay-shadow-primary: rgba(0, 0, 0, 0.25);
   --typeahead-overlay-shadow-secondary: rgba(0, 0, 0, 0.4);
   --spoiler-text-color: var(--spoiler-color);
   --spoiler-background-color: var(--spoiler-color);
   --purple-link: var(--violet-light-100);
   --drawer-expand-button: var(--shades-black-60);
   --drawer-expand-button-disabled: var(--shades-black-80);
   --drawer-item-color: var(--shades-white-60);
   --drawer-active-item-color: var(--shades-white-100);
   --drawer-open-community-bg: #191919;
   --active-drawer-item-bg: rgba(0, 0, 0, 0.5);
   --community-drawer-lines: rgba(255, 255, 255, 0.08);
   --topbar-button-bg: var(--shades-black-90);
   --filters-button-bg: var(--shades-black-100);
   --filters-button-border: var(--shades-black-80);
   --filters-button-hover-bg: var(--shades-black-90);
   --filter-panel-fg: var(--shades-black-60);
   --filter-panel-bg: #0d0d0d;
   --topbar-button-bg-hover: var(--shades-black-80);
   --topbar-button-fg: var(--shades-white-60);
   --message-label-color: var(--shades-black-60);
   --topbar-lines: rgba(255, 255, 255, 0.08);
   --pin-message-information-text-color: var(--shades-white-60);
   --pin-message-modal-border-color: var(--shades-black-80);
   --pinned-count-banner-color: var(--shades-black-90);
   --pinned-count-text-color: var(--shades-white-90);
   --modal-overlay-background-90: rgba(0, 0, 0, 0.9);
   --modal-overlay-background-80: rgba(0, 0, 0, 0.8);
   --edit-avatar-button: var(--violet-dark-60);
   --dropdown-text: var(--shades-white-100);
   --dropdown-select-bg: var(--shades-black-90);
   --dropdown-select-border: var(--shades-white-60);
   --dropdown-option-bg: var(--shades-black-80);
   --dropdown-option-hover-bg: var(--shades-black-70);
   --dropdown-selected-option-check-color: var(--violet-dark-100);
   --dropdown-disabled-color: var(--shades-black-60);
   --change-member-role-modal-description-text: var(--shades-white-60);
   --change-member-role-modal-generic-text: var(--shades-white-100);
+  --change-member-role-modal-disabled-background: var(--shades-black-80);
   --unsaved-changes-modal-text-color: var(--shades-white-60);
 }