diff --git a/isic/core/api/image.py b/isic/core/api/image.py
index 3276c55f..a0a69cfa 100644
--- a/isic/core/api/image.py
+++ b/isic/core/api/image.py
@@ -309,6 +309,8 @@ def image_set_pinned(request, id: int, payload: SetPinned):
     qs = get_visible_objects(request.user, "core.view_image", Image.objects.all())
     image = get_object_or_404(qs.distinct(), id=id)
     if payload.pinned:
+        if not image.public:
+            return 400, {"error": "Cannot pin a private image."}
         last_pin = Image.objects.aggregate(Max("pinned")).get("pinned__max") or 0
         image.pinned = last_pin + 1
     else:
diff --git a/isic/core/migrations/0043_image_image_pinned_implies_public.py b/isic/core/migrations/0043_image_image_pinned_implies_public.py
new file mode 100644
index 00000000..09d89d14
--- /dev/null
+++ b/isic/core/migrations/0043_image_image_pinned_implies_public.py
@@ -0,0 +1,22 @@
+# Generated by Django 5.2.15 on 2026-07-02 17:17
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("core", "0042_pinned_images"),
+        ("ingest", "0043_alter_rcmcase_id"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.AddConstraint(
+            model_name="image",
+            constraint=models.CheckConstraint(
+                condition=models.Q(("pinned__isnull", True), ("public", True), _connector="OR"),
+                name="image_pinned_implies_public",
+            ),
+        ),
+    ]
diff --git a/isic/core/models/image.py b/isic/core/models/image.py
index 42e53c7f..5e3f445d 100644
--- a/isic/core/models/image.py
+++ b/isic/core/models/image.py
@@ -68,6 +68,13 @@ class Image(CreationSortedTimeStampedModel):
     class Meta(CreationSortedTimeStampedModel.Meta):
         ordering = ["created"]
 
+        constraints = [
+            CheckConstraint(
+                name="image_pinned_implies_public",
+                condition=Q(pinned__isnull=True) | Q(public=True),
+            ),
+        ]
+
         indexes = [
             # icontains uses Upper(name) for searching
             GinIndex(OpClass(Upper("isic"), name="gin_trgm_ops"), name="isic_name_gin"),
diff --git a/isic/core/templates/core/image_detail/actions_menu.html b/isic/core/templates/core/image_detail/actions_menu.html
index ec01a76a..59c8d48f 100644
--- a/isic/core/templates/core/image_detail/actions_menu.html
+++ b/isic/core/templates/core/image_detail/actions_menu.html
@@ -10,10 +10,21 @@
       <li>
         <button @click="setPinned(false)">Unpin Image</button>
       </li>
-    {% else %}
+    {% elif image.public %}
       <li>
         <button @click="setPinned(true)">Pin Image</button>
       </li>
+    {% else %}
+      {% with pin_disabled_reason="Only public images can be pinned" %}
+        <li>
+          <span class="tooltip tooltip-left w-full" data-tip="{{ pin_disabled_reason }}">
+            <button class="w-full text-left" disabled aria-describedby="pin-disabled-reason">
+              Pin Image
+            </button>
+          </span>
+          <span id="pin-disabled-reason" class="sr-only">{{ pin_disabled_reason }}</span>
+        </li>
+      {% endwith %}
     {% endif %}
   {% endif %}
 </ul>
diff --git a/isic/core/tests/test_image_pin.py b/isic/core/tests/test_image_pin.py
index 6f81b6b3..df9fab02 100644
--- a/isic/core/tests/test_image_pin.py
+++ b/isic/core/tests/test_image_pin.py
@@ -30,6 +30,19 @@ def test_core_api_image_set_pinned_permissions(client_, expected_status, image_f
         assert image.pinned is None
 
 
+@pytest.mark.django_db
+def test_core_api_image_set_pinned_private_image_rejected(staff_client, image_factory):
+    image = image_factory(public=False)
+    r = staff_client.post(
+        reverse("api:image_set_pinned", kwargs={"id": image.pk}),
+        {"pinned": True},
+        content_type="application/json",
+    )
+    assert r.status_code == 400
+    image.refresh_from_db()
+    assert image.pinned is None
+
+
 @pytest.mark.django_db
 def test_core_api_image_sort_by_pinned(image_factory, authenticated_client):
     image_1 = image_factory(public=True)
@@ -49,7 +62,7 @@ def test_core_api_image_sort_by_pinned(image_factory, authenticated_client):
 @pytest.mark.playwright
 def test_image_pin_unpin(image_factory, staff_authenticated_page):
     page = staff_authenticated_page
-    image_id = image_factory().isic_id
+    image_id = image_factory(public=True).isic_id
     page.goto(reverse("core/image-detail", args=[image_id]))
 
     # Pin the image
@@ -70,3 +83,15 @@ def test_image_pin_unpin(image_factory, staff_authenticated_page):
     # Pin button should be back
     page.get_by_role("button", name="Actions").click()
     expect(page.get_by_role("button", name="Pin image")).to_be_visible()
+
+
+@pytest.mark.playwright
+def test_image_pin_disabled_when_private(image_factory, staff_authenticated_page):
+    page = staff_authenticated_page
+    image_id = image_factory(public=False).isic_id
+    page.goto(reverse("core/image-detail", args=[image_id]))
+
+    page.get_by_role("button", name="Actions").click()
+    pin_button = page.get_by_role("button", name="Pin image")
+    expect(pin_button).to_be_disabled()
+    expect(pin_button).to_have_accessible_description("Only public images can be pinned")