diff --git a/components/admin/org/__tests__/shared-tags-section.test.tsx b/components/admin/org/__tests__/shared-tags-section.test.tsx
new file mode 100644
index 000000000..621994ded
--- /dev/null
+++ b/components/admin/org/__tests__/shared-tags-section.test.tsx
@@ -0,0 +1,78 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { act, fireEvent, render, screen, waitFor, within } from '@testing-library/react';
+
+// Organisation > Sharing > Shared tags: one sentence and the lock for the
+// `sharedTags` restriction, written at the scope chosen in the scope bar.
+
+const puts: Array<Record<string, unknown>> = [];
+let stored: Record<string, unknown> = {};
+vi.mock('@/lib/browser-navigation', () => ({
+  apiFetch: vi.fn(async (_url: string, init?: RequestInit) => {
+    if (init?.method === 'PUT') {
+      const body = JSON.parse(String(init.body));
+      puts.push(body);
+      stored = body;
+      return new Response('{"ok":true}');
+    }
+    return new Response(JSON.stringify(stored));
+  }),
+  withBasePath: (p: string) => p,
+  getPathPrefix: () => '',
+}));
+
+import { SharedTagsSection } from '../sections/shared-tags-section';
+import { useOrgPolicyDraft, useOrgScopeStore, EVERYONE } from '../use-org-policy-draft';
+import { RESTRICTION_KEYS } from '@/lib/admin/restriction-keys';
+import { resolvePolicy } from '@/lib/admin/policy-scopes';
+
+const POLICY = {
+  restrictions: {}, features: {}, defaults: {}, themePolicy: {},
+  forceEnabledPlugins: [], approvedPlugins: [], forceEnabledThemes: [],
+  scopes: [{ id: 'leads', label: 'Leads', match: { groups: ['leads@example.org'] }, policy: {} }],
+};
+
+let latest: ReturnType<typeof useOrgPolicyDraft> | null = null;
+function Harness() {
+  const draft = useOrgPolicyDraft('test');
+  latest = draft;
+  if (draft.loading) return null;
+  return <SharedTagsSection draft={draft} />;
+}
+
+beforeEach(() => {
+  puts.length = 0;
+  stored = JSON.parse(JSON.stringify(POLICY));
+  latest = null;
+  useOrgScopeStore.setState({ scopeId: EVERYONE });
+});
+
+describe('Shared tags section', () => {
+  it('registers sharedTags on the Sharing page, lock only', () => {
+    expect(RESTRICTION_KEYS.find((def) => def.key === 'sharedTags')).toMatchObject({ page: 'org-sharing', modes: ['locked'] });
+  });
+
+  it('locks shared tags for everyone and unlocks them in a group scope', async () => {
+    render(<Harness />);
+    const section = await screen.findByTestId('org-shared-tags-section');
+    expect(within(section).queryByText('Hide')).not.toBeInTheDocument();
+
+    fireEvent.click(within(section).getByRole('checkbox'));
+    expect(latest!.policy?.restrictions.sharedTags).toEqual({ locked: true });
+
+    act(() => latest!.setScopeId('leads'));
+    await waitFor(() => expect(within(screen.getByTestId('org-shared-tags-section')).getByRole('checkbox')).toBeChecked());
+    fireEvent.click(within(screen.getByTestId('org-shared-tags-section')).getByRole('checkbox'));
+    // In a scope an empty restriction is a real override: it unlocks.
+    expect(latest!.policy?.scopes?.[0].policy.restrictions?.sharedTags).toEqual({});
+    const lead = resolvePolicy(latest!.policy!, { email: 'anna@example.org', groups: ['leads@example.org'] }).policy;
+    const member = resolvePolicy(latest!.policy!, { email: 'bob@example.org', groups: ['team@example.org'] }).policy;
+    expect(lead.restrictions.sharedTags?.locked).not.toBe(true);
+    expect(member.restrictions.sharedTags?.locked).toBe(true);
+
+    await act(async () => { await latest!.save(); });
+    expect(puts[0]).toMatchObject({
+      restrictions: { sharedTags: { locked: true } },
+      scopes: [{ id: 'leads', policy: { restrictions: { sharedTags: {} } } }],
+    });
+  });
+});
diff --git a/components/admin/org/sections/shared-tags-section.tsx b/components/admin/org/sections/shared-tags-section.tsx
index 978c1a56d..847748d3c 100644
--- a/components/admin/org/sections/shared-tags-section.tsx
+++ b/components/admin/org/sections/shared-tags-section.tsx
@@ -1,14 +1,27 @@
 'use client';
 
 import { SettingsSection } from '@/components/settings/settings-section';
+import { restrictionKeysForPage } from '@/lib/admin/restriction-keys';
+import { RestrictionRow } from '../org-page';
 import type { OrgPolicyDraft } from '../use-org-policy-draft';
 
-/** Organisation feature 6; filled in by its own step (local-data/org-features-plan.md). */
+/**
+ * Organisation feature 6: shared tags in group mailboxes. The tags live in
+ * the group's Inbox on the mail server (Stalwart 1.0 metadata), so the only
+ * thing to set here is who may change them.
+ */
 export function SharedTagsSection({ draft }: { draft: OrgPolicyDraft }) {
-  void draft;
   return (
-    <SettingsSection id="shared-tags" title="Shared tags" description="Tag names and colours that every member of a shared mailbox sees.">
-      <p className="text-sm text-muted-foreground">Nothing to set here yet.</p>
+    <SettingsSection
+      id="shared-tags"
+      title="Shared tags"
+      description="Members of a group mailbox see the same tag names and colours on its mail, and members who may change the mailbox edit them (Stalwart 1.0 or later)."
+    >
+      <div data-testid="org-shared-tags-section">
+        {restrictionKeysForPage('org-sharing')
+          .filter((def) => def.key === 'sharedTags')
+          .map((def) => <RestrictionRow key={def.key} draft={draft} def={def} />)}
+      </div>
     </SettingsSection>
   );
 }
diff --git a/lib/admin/restriction-keys.ts b/lib/admin/restriction-keys.ts
index 7d00d4103..92b21d081 100644
--- a/lib/admin/restriction-keys.ts
+++ b/lib/admin/restriction-keys.ts
@@ -51,6 +51,15 @@ export const RESTRICTION_KEYS: readonly RestrictionKeyDef[] = [
     page: 'org-signatures',
     modes: ['locked', 'hidden'],
   },
+  {
+    key: 'sharedTags',
+    label: 'Shared tags',
+    description: "Lock: users can tag mail with the shared tags of their group mailboxes but can't add, rename or delete them. Unlock it in a group scope for the people who look after the tags.",
+    category: 'Sharing',
+    type: 'boolean',
+    page: 'org-sharing',
+    modes: ['locked'],
+  },
 ];
 
 export function restrictionKeysForPage(page: AdminPageId): RestrictionKeyDef[] {