diff --git a/native/roles/change-roles-header-right-button.react.js b/native/roles/change-roles-header-right-button.react.js
--- a/native/roles/change-roles-header-right-button.react.js
+++ b/native/roles/change-roles-header-right-button.react.js
@@ -3,7 +3,7 @@
 import { useNavigation } from '@react-navigation/native';
 import invariant from 'invariant';
 import * as React from 'react';
-import { Text } from 'react-native';
+import { Text, View } from 'react-native';
 import { TouchableOpacity } from 'react-native-gesture-handler';
 
 import {
@@ -20,24 +20,27 @@
 
 type Props = {
   +route: NavigationRoute<'ChangeRolesScreen'>,
+  +shouldRoleChangeBeDisabled: boolean,
 };
 
 function ChangeRolesHeaderRightButton(props: Props): React.Node {
   const { threadInfo, memberInfo, role: selectedRole } = props.route.params;
+  const { shouldRoleChangeBeDisabled } = props;
   const { role: initialRole } = memberInfo;
+  invariant(initialRole, 'Expected initial role to be defined');
   invariant(selectedRole, 'Expected selected role to be defined');
   const navigation = useNavigation();
 
   const callChangeThreadMemberRoles = useServerCall(changeThreadMemberRoles);
   const dispatchActionPromise = useDispatchActionPromise();
 
-  const { purpleLink } = useColors();
+  const { disabledButton, purpleLink } = useColors();
   const textStyle = React.useMemo(
     () => ({
-      color: purpleLink,
+      color: shouldRoleChangeBeDisabled ? disabledButton : purpleLink,
       marginRight: 10,
     }),
-    [purpleLink],
+    [disabledButton, purpleLink, shouldRoleChangeBeDisabled],
   );
 
   const handleSave = React.useCallback(() => {
@@ -62,11 +65,23 @@
     threadInfo.id,
   ]);
 
-  return (
-    <TouchableOpacity onPress={handleSave}>
-      <Text style={textStyle}>Save</Text>
-    </TouchableOpacity>
-  );
+  const saveButton = React.useMemo(() => {
+    if (shouldRoleChangeBeDisabled) {
+      return (
+        <View>
+          <Text style={textStyle}>Save</Text>
+        </View>
+      );
+    }
+
+    return (
+      <TouchableOpacity onPress={handleSave}>
+        <Text style={textStyle}>Save</Text>
+      </TouchableOpacity>
+    );
+  }, [shouldRoleChangeBeDisabled, textStyle, handleSave]);
+
+  return saveButton;
 }
 
 export default ChangeRolesHeaderRightButton;
diff --git a/native/roles/change-roles-screen.react.js b/native/roles/change-roles-screen.react.js
--- a/native/roles/change-roles-screen.react.js
+++ b/native/roles/change-roles-screen.react.js
@@ -9,6 +9,8 @@
 
 import { changeThreadMemberRolesActionTypes } from 'lib/actions/thread-actions.js';
 import { createLoadingStatusSelector } from 'lib/selectors/loading-selectors.js';
+import { otherUsersButNoOtherAdmins } from 'lib/selectors/thread-selectors.js';
+import { roleIsAdminRole } from 'lib/shared/thread-utils.js';
 import type { LoadingStatus } from 'lib/types/loading-types.js';
 import type { RelativeMemberInfo, ThreadInfo } from 'lib/types/thread-types.js';
 import { values } from 'lib/utils/objects.js';
@@ -120,6 +122,62 @@
     showActionSheetWithOptions,
   ]);
 
+  const otherUsersButNoOtherAdminsValue = useSelector(
+    otherUsersButNoOtherAdmins(threadInfo.id),
+  );
+
+  const memberIsAdmin = React.useMemo(() => {
+    invariant(memberInfo.role, 'Expected member role to be defined');
+    return roleIsAdminRole(threadInfo.roles[memberInfo.role]);
+  }, [threadInfo.roles, memberInfo.role]);
+
+  const shouldRoleChangeBeDisabled = React.useMemo(
+    () => otherUsersButNoOtherAdminsValue && memberIsAdmin,
+    [otherUsersButNoOtherAdminsValue, memberIsAdmin],
+  );
+
+  const roleSelector = React.useMemo(() => {
+    if (shouldRoleChangeBeDisabled) {
+      return (
+        <View style={styles.roleSelector}>
+          <Text style={styles.disabledCurrentRole}>{selectedRoleName}</Text>
+          <SWMansionIcon
+            name="edit-1"
+            size={20}
+            style={styles.disabledPencilIcon}
+          />
+        </View>
+      );
+    }
+
+    return (
+      <TouchableOpacity onPress={showActionSheet} style={styles.roleSelector}>
+        <Text style={styles.currentRole}>{selectedRoleName}</Text>
+        <SWMansionIcon name="edit-1" size={20} style={styles.pencilIcon} />
+      </TouchableOpacity>
+    );
+  }, [showActionSheet, styles, selectedRoleName, shouldRoleChangeBeDisabled]);
+
+  const disabledRoleChangeMessage = React.useMemo(() => {
+    if (!shouldRoleChangeBeDisabled) {
+      return null;
+    }
+
+    return (
+      <View style={styles.disabledWarningBackground}>
+        <SWMansionIcon name="info-circle" size={24} style={styles.infoIcon} />
+        <Text style={styles.disabledWarningText}>
+          There must be at least one admin at any given time in a community.
+        </Text>
+      </View>
+    );
+  }, [
+    shouldRoleChangeBeDisabled,
+    styles.disabledWarningBackground,
+    styles.infoIcon,
+    styles.disabledWarningText,
+  ]);
+
   React.useEffect(() => {
     navigation.setOptions({
       // eslint-disable-next-line react/display-name
@@ -133,10 +191,21 @@
             />
           );
         }
-        return <ChangeRolesHeaderRightButton route={route} />;
+        return (
+          <ChangeRolesHeaderRightButton
+            route={route}
+            shouldRoleChangeBeDisabled={shouldRoleChangeBeDisabled}
+          />
+        );
       },
     });
-  }, [changeRolesLoadingStatus, navigation, activityIndicatorStyle, route]);
+  }, [
+    changeRolesLoadingStatus,
+    navigation,
+    activityIndicatorStyle,
+    route,
+    shouldRoleChangeBeDisabled,
+  ]);
 
   return (
     <View>
@@ -150,13 +219,8 @@
         <UserAvatar userID={memberInfo.id} size="profile" />
         <Text style={styles.memberInfoUsername}>{memberInfo.username}</Text>
       </View>
-      <View>
-        <Text style={styles.roleSelectorLabel}>ROLE</Text>
-        <TouchableOpacity onPress={showActionSheet} style={styles.roleSelector}>
-          <Text style={styles.currentRole}>{selectedRoleName}</Text>
-          <SWMansionIcon name="edit-1" size={20} style={styles.pencilIcon} />
-        </TouchableOpacity>
-      </View>
+      {roleSelector}
+      {disabledRoleChangeMessage}
     </View>
   );
 }
@@ -203,9 +267,39 @@
     color: 'panelForegroundSecondaryLabel',
     fontSize: 16,
   },
+  disabledCurrentRole: {
+    color: 'disabledButton',
+    fontSize: 16,
+  },
   pencilIcon: {
     color: 'panelInputSecondaryForeground',
   },
+  disabledPencilIcon: {
+    color: 'disabledButton',
+  },
+  disabledWarningBackground: {
+    backgroundColor: 'disabledButton',
+    color: 'green',
+    padding: 16,
+    display: 'flex',
+    marginTop: 20,
+    flexDirection: 'row',
+    justifyContent: 'center',
+    width: '75%',
+    alignSelf: 'center',
+  },
+  disabledWarningText: {
+    color: 'panelForegroundSecondaryLabel',
+    fontSize: 14,
+    marginRight: 8,
+    display: 'flex',
+  },
+  infoIcon: {
+    color: 'panelForegroundSecondaryLabel',
+    marginRight: 8,
+    marginLeft: 8,
+    marginBottom: 12,
+  },
 };
 
 export default ChangeRolesScreen;