diff --git a/frontend/src/app/(admin)/admin/organizations/[orgId]/page.tsx b/frontend/src/app/(admin)/admin/organizations/[orgId]/page.tsx
index d4e14a05..b4e25166 100644
--- a/frontend/src/app/(admin)/admin/organizations/[orgId]/page.tsx
+++ b/frontend/src/app/(admin)/admin/organizations/[orgId]/page.tsx
@@ -19,6 +19,7 @@ import { OrganizationCourseDrawer } from "@/components/admin/organization-course
 import {
   createOrganizationCouponPoolAction,
   rotateOrganizationCredentialFormAction,
+  setAllocationAllowedAction,
   setAllocationLeaderboardAction,
   setOrganizationCouponPoolActiveAction,
 } from "@/server/actions/admin/organizations";
@@ -200,7 +201,7 @@ export default async function AdminOrganizationDetailPage({
               <AdminTableHeaderCell>Course</AdminTableHeaderCell>
               <AdminTableHeaderCell align="right">Used / max</AdminTableHeaderCell>
               <AdminTableHeaderCell>Expires</AdminTableHeaderCell>
-              <AdminTableHeaderCell>Allowed</AdminTableHeaderCell>
+              <AdminTableHeaderCell>Assignable</AdminTableHeaderCell>
               <AdminTableHeaderCell>Leaderboards</AdminTableHeaderCell>
             </tr>
           </AdminTableHead>
@@ -230,11 +231,26 @@ export default async function AdminOrganizationDetailPage({
                     {row.expiresAt ? new Date(row.expiresAt).toLocaleDateString() : "—"}
                   </AdminTableCell>
                   <AdminTableCell>
-                    {row.isAllowed ? (
-                      <Badge variant="secondary">Yes</Badge>
-                    ) : (
-                      <Badge variant="outline">No</Badge>
-                    )}
+                    <form action={setAllocationAllowedAction} className="flex items-center gap-2">
+                      <input type="hidden" name="organizationId" value={org.id} />
+                      <input type="hidden" name="courseId" value={row.course.id} />
+                      <input type="hidden" name="enabled" value={row.isAllowed ? "false" : "true"} />
+                      {row.isAllowed ? (
+                        <Badge variant="secondary">Yes</Badge>
+                      ) : (
+                        <Badge variant="destructive" title="The integration cannot see this course, so it cannot be assigned">
+                          Not assignable
+                        </Badge>
+                      )}
+                      <Button
+                        type="submit"
+                        size="sm"
+                        variant="ghost"
+                        aria-label={`${row.isAllowed ? "Turn off" : "Turn on"} integration enrollments for ${row.course.title}`}
+                      >
+                        {row.isAllowed ? "Turn off" : "Turn on"}
+                      </Button>
+                    </form>
                   </AdminTableCell>
                   <AdminTableCell>
                     <form action={setAllocationLeaderboardAction} className="flex items-center gap-2">
diff --git a/frontend/src/server/actions/admin/organizations.ts b/frontend/src/server/actions/admin/organizations.ts
index e271a732..ecfd2987 100644
--- a/frontend/src/server/actions/admin/organizations.ts
+++ b/frontend/src/server/actions/admin/organizations.ts
@@ -83,6 +83,23 @@ export async function bulkUpsertOrganizationCourseAllocationsAction(
   });
 }
 
+/**
+ * Turns integration enrollments on or off for one allocated course. This is the
+ * flag the integration catalog filters on, so a course with it off cannot be
+ * assigned even though it sits in the organization's catalog.
+ */
+export async function setAllocationAllowedAction(formData: FormData): Promise<void> {
+  const organizationId = String(formData.get("organizationId") ?? "");
+  const courseId = String(formData.get("courseId") ?? "");
+  if (!organizationId || !courseId) throw new Error("Missing organization or course.");
+  await adminCall(
+    `/api/v1/admin/organizations/${encodeURIComponent(organizationId)}/allocations/${encodeURIComponent(courseId)}/allowed`,
+    { method: "PATCH", json: { enabled: formData.get("enabled") === "true" } }
+  );
+  revalidatePath(`/admin/organizations/${organizationId}`);
+  revalidatePath("/admin/organizations");
+}
+
 /** Lets (or stops) an organization's learners joining a course's weekly leaderboards. */
 export async function setAllocationLeaderboardAction(formData: FormData): Promise<void> {
   const organizationId = String(formData.get("organizationId") ?? "");
diff --git a/server/src/controllers/admin.ts b/server/src/controllers/admin.ts
index 653a90b0..4d346642 100644
--- a/server/src/controllers/admin.ts
+++ b/server/src/controllers/admin.ts
@@ -119,6 +119,13 @@ export async function bulkRejectCourseRequests(req: Request, res: Response) {
   ok(res, await courseRequests.bulkRejectCourseRequests(req.user!, ids));
 }
 
+// PATCH /api/v1/admin/organizations/:orgId/allocations/:courseId/allowed
+export async function setAllocationAllowed(req: Request, res: Response) {
+  const { enabled } = req.body as { enabled: boolean };
+  await organizations.setAllocationAllowed(req.user!, param(req, "orgId"), param(req, "courseId"), enabled);
+  noContent(res);
+}
+
 // PATCH /api/v1/admin/organizations/:orgId/allocations/:courseId/leaderboard
 export async function setAllocationLeaderboard(req: Request, res: Response) {
   const { enabled } = req.body as { enabled: boolean };
diff --git a/server/src/routes/v1/admin.ts b/server/src/routes/v1/admin.ts
index 816bd060..b91935bf 100644
--- a/server/src/routes/v1/admin.ts
+++ b/server/src/routes/v1/admin.ts
@@ -95,6 +95,11 @@ router.post("/organizations", validateBody(createOrganizationBody), admin.create
 router.get("/organizations/:orgId", validateParams(orgIdParams), admin.getOrganization);
 router.post("/organizations/:orgId/credentials/rotate", validateParams(orgIdParams), admin.rotateCredential);
 router.put("/organizations/:orgId/allocations", validate({ params: orgIdParams, body: allocationsBody }), admin.upsertAllocations);
+router.patch(
+  "/organizations/:orgId/allocations/:courseId/allowed",
+  validate({ params: allocationParams, body: instructorAccessBody }),
+  admin.setAllocationAllowed
+);
 router.patch(
   "/organizations/:orgId/allocations/:courseId/leaderboard",
   validate({ params: allocationParams, body: instructorAccessBody }),
diff --git a/server/src/services/admin/organizations.ts b/server/src/services/admin/organizations.ts
index 319e00c9..16737c8a 100644
--- a/server/src/services/admin/organizations.ts
+++ b/server/src/services/admin/organizations.ts
@@ -248,6 +248,46 @@ export function approvePendingRequestsFor(tx: Prisma.TransactionClient, organiza
   });
 }
 
+/**
+ * Switches integration enrollments on or off for ONE allocation.
+ *
+ * `isAllowed` is the flag `/integrations/v1/courses` filters on, so an
+ * allocation with it off is invisible to the organisation's integration even
+ * though the catalog shows it in place with seats and no expiry. Until this
+ * existed the flag could only be set by the bulk form's single checkbox, which
+ * applies to every selected course at once — so one save with it unticked left
+ * a whole catalog unassignable, with no way back but re-selecting everything.
+ *
+ * Audited like a bulk allocation change, because it grants or withdraws access.
+ */
+export async function setAllocationAllowed(
+  actor: AdminActor,
+  orgId: string,
+  courseId: string,
+  isAllowed: boolean
+): Promise<void> {
+  const allocation = await prisma.organizationCourse.findUnique({
+    where: { organizationId_courseId: { organizationId: orgId, courseId } },
+    select: { organization: { select: { name: true } }, course: { select: { title: true } } },
+  });
+  if (!allocation) throw new NotFoundError("Allocation not found");
+
+  await prisma.$transaction(async (tx) => {
+    await tx.organizationCourse.update({
+      where: { organizationId_courseId: { organizationId: orgId, courseId } },
+      data: { isAllowed },
+    });
+    await recordAdminAction(tx, {
+      actor,
+      action: ADMIN_AUDIT_ACTIONS.ORGANIZATION_ALLOCATE,
+      targetType: "Organization",
+      targetId: orgId,
+      summary: `${isAllowed ? "Enabled" : "Disabled"} integration enrollments for ${allocation.course.title} at ${allocation.organization.name}`,
+      metadata: { courseIds: [courseId], isAllowed },
+    });
+  });
+}
+
 /** Lets (or stops) this organization's learners joining the course's weekly leaderboards. */
 export async function setAllocationLeaderboard(orgId: string, courseId: string, enabled: boolean): Promise<void> {
   const { count } = await prisma.organizationCourse.updateMany({
diff --git a/server/tests/api/admin.test.ts b/server/tests/api/admin.test.ts
index e73474e6..b0868c8d 100644
--- a/server/tests/api/admin.test.ts
+++ b/server/tests/api/admin.test.ts
@@ -119,6 +119,31 @@ describe("organizations", () => {
     expect(bad.status).toBe(422);
     expect(bad.body.code).toBe("COURSE_NOT_PUBLISHED");
   });
+
+  it("turns integration enrollments off and back on for a single allocation", async () => {
+    await request(app)
+      .put(`/api/v1/admin/organizations/${createdOrgId}/allocations`)
+      .set(admin())
+      .send({ isAllowed: true, courses: [{ courseId: fx.course.id, maxEnrollments: 25 }] });
+
+    const url = `/api/v1/admin/organizations/${createdOrgId}/allocations/${fx.course.id}/allowed`;
+    const key = { organizationId_courseId: { organizationId: createdOrgId, courseId: fx.course.id } };
+
+    const off = await request(app).patch(url).set(admin()).send({ enabled: false });
+    expect(off.status).toBe(204);
+    expect(await prisma.organizationCourse.findUnique({ where: key })).toMatchObject({ isAllowed: false, maxEnrollments: 25 });
+
+    const on = await request(app).patch(url).set(admin()).send({ enabled: true });
+    expect(on.status).toBe(204);
+    expect(await prisma.organizationCourse.findUnique({ where: key })).toMatchObject({ isAllowed: true, maxEnrollments: 25 });
+
+    // An allocation that does not exist is a 404, not a silent no-op.
+    const missing = await request(app)
+      .patch(`/api/v1/admin/organizations/${createdOrgId}/allocations/${org.organization.id}/allowed`)
+      .set(admin())
+      .send({ enabled: true });
+    expect(missing.status).toBe(404);
+  });
 });
 
 describe("course requests", () => {
diff --git a/server/tests/api/integrations.test.ts b/server/tests/api/integrations.test.ts
index 559e627e..03f85066 100644
--- a/server/tests/api/integrations.test.ts
+++ b/server/tests/api/integrations.test.ts
@@ -48,6 +48,32 @@ describe("/integrations/v1 (public organisation API)", () => {
     expect(allocations.body.allocations[0]).toMatchObject({ course_id: fx.course.id, max_enrollments: 1, current_enrollments: 0 });
   });
 
+  // A catalog that looks complete but is switched off reads as "no courses" to
+  // the consumer, which is indistinguishable from "nothing allocated". The
+  // allocations endpoint is what tells the two apart.
+  it("hides a course from the catalog while it is not allowed, but still reports the allocation", async () => {
+    const key = { organizationId_courseId: { organizationId: org.organization.id, courseId: fx.course.id } };
+    await prisma.organizationCourse.update({ where: key, data: { isAllowed: false } });
+    try {
+      const courses = await request(app).get("/integrations/v1/courses").set(org.headers);
+      expect(courses.status).toBe(200);
+      expect(courses.body.courses).toEqual([]);
+
+      const allocations = await request(app).get("/integrations/v1/allocations").set(org.headers);
+      expect(allocations.body.allocations).toHaveLength(1);
+      expect(allocations.body.allocations[0]).toMatchObject({
+        course_id: fx.course.id,
+        is_allowed: false,
+        course_status: "PUBLISHED",
+      });
+    } finally {
+      await prisma.organizationCourse.update({ where: key, data: { isAllowed: true } });
+    }
+
+    const restored = await request(app).get("/integrations/v1/courses").set(org.headers);
+    expect(restored.body.courses).toHaveLength(1);
+  });
+
   it("creates an enrollment once, consumes the slot, then reports it", async () => {
     const payload = { student_email: `new-${fx.tag}@test.local`, course_id: fx.course.id, external_assignment_id: `assign-${fx.tag}` };