diff --git a/.changeset/organization-response-types.md b/.changeset/organization-response-types.md
new file mode 100644
index 0000000..80902cd
--- /dev/null
+++ b/.changeset/organization-response-types.md
@@ -0,0 +1,11 @@
+---
+'@seamless-auth/react': patch
+---
+
+Correct the organization response types, checked against the API's declared response schemas.
+
+- `addOrganizationMember` and `updateOrganizationMember` return `OrganizationMembershipResult` (`{ membership }`). They were typed as returning a members list, so reading `.members` gave `undefined`.
+- `removeOrganizationMember` returns `MessageResult`, not a members list.
+- `switchOrganization` returns `OrganizationSwitchResult` (`{ message, organizationId, organization }`), which describes what the endpoint actually sends.
+
+`OrganizationMembershipResult` and `OrganizationSwitchResult` are new exports.
diff --git a/src/client/createSeamlessAuthClient.ts b/src/client/createSeamlessAuthClient.ts
index af5ff62..7af2058 100644
--- a/src/client/createSeamlessAuthClient.ts
+++ b/src/client/createSeamlessAuthClient.ts
@@ -103,6 +103,22 @@ export interface OrganizationMembersResult {
   total: number;
 }
 
+/** Response body for a single membership mutation. */
+export interface OrganizationMembershipResult {
+  membership: OrganizationMembership;
+}
+
+/**
+ * Response body when the active organization changes. The server also returns
+ * session material here, which this SDK deliberately does not surface: sessions
+ * are carried by cookies, so adopters have no reason to handle raw tokens.
+ */
+export interface OrganizationSwitchResult {
+  message: string;
+  organizationId: string;
+  organization: Organization;
+}
+
 export interface OAuthProvider {
   id: string;
   name: string;
@@ -278,23 +294,23 @@ export interface SeamlessAuthClient {
   ) => Promise<SeamlessAuthResult<OrganizationResult>>;
   switchOrganization: (
     organizationId: string
-  ) => Promise<SeamlessAuthResult<OrganizationResult>>;
+  ) => Promise<SeamlessAuthResult<OrganizationSwitchResult>>;
   listOrganizationMembers: (
     organizationId: string
   ) => Promise<SeamlessAuthResult<OrganizationMembersResult>>;
   addOrganizationMember: (
     organizationId: string,
     input: OrganizationMemberInput
-  ) => Promise<SeamlessAuthResult<OrganizationMembersResult>>;
+  ) => Promise<SeamlessAuthResult<OrganizationMembershipResult>>;
   updateOrganizationMember: (
     organizationId: string,
     userId: string,
     input: OrganizationMemberUpdateInput
-  ) => Promise<SeamlessAuthResult<OrganizationMembersResult>>;
+  ) => Promise<SeamlessAuthResult<OrganizationMembershipResult>>;
   removeOrganizationMember: (
     organizationId: string,
     userId: string
-  ) => Promise<SeamlessAuthResult<OrganizationMembersResult>>;
+  ) => Promise<SeamlessAuthResult<MessageResult>>;
 }
 
 type StepUpPayload = Partial<StepUpStatus> & { message?: string };
@@ -814,7 +830,7 @@ export const createSeamlessAuthClient = (
       ),
 
     switchOrganization: organizationId =>
-      requestResult<OrganizationResult>(
+      requestResult<OrganizationSwitchResult>(
         fetchWithAuth(`/organizations/${encodeURIComponent(organizationId)}/switch`, {
           method: 'POST',
         }),
@@ -830,7 +846,7 @@ export const createSeamlessAuthClient = (
       ),
 
     addOrganizationMember: (organizationId, input) =>
-      requestResult<OrganizationMembersResult>(
+      requestResult<OrganizationMembershipResult>(
         fetchWithAuth(`/organizations/${encodeURIComponent(organizationId)}/members`, {
           method: 'POST',
           body: JSON.stringify(input),
@@ -839,7 +855,7 @@ export const createSeamlessAuthClient = (
       ),
 
     updateOrganizationMember: (organizationId, userId, input) =>
-      requestResult<OrganizationMembersResult>(
+      requestResult<OrganizationMembershipResult>(
         fetchWithAuth(
           `/organizations/${encodeURIComponent(organizationId)}/members/${encodeURIComponent(userId)}`,
           {
@@ -851,7 +867,7 @@ export const createSeamlessAuthClient = (
       ),
 
     removeOrganizationMember: (organizationId, userId) =>
-      requestResult<OrganizationMembersResult>(
+      requestResult<MessageResult>(
         fetchWithAuth(
           `/organizations/${encodeURIComponent(organizationId)}/members/${encodeURIComponent(userId)}`,
           {
diff --git a/src/index.ts b/src/index.ts
index 5cf2250..474dbc9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -21,7 +21,9 @@ import {
   OrganizationMemberInput,
   OrganizationMemberUpdateInput,
   OrganizationMembersResult,
+  OrganizationMembershipResult,
   OrganizationResult,
+  OrganizationSwitchResult,
   OrganizationsResult,
   PasskeyLoginData,
   PasskeyMetadata,
@@ -85,7 +87,9 @@ export type {
   OrganizationMembership,
   OrganizationMemberUpdateInput,
   OrganizationMembersResult,
+  OrganizationMembershipResult,
   OrganizationResult,
+  OrganizationSwitchResult,
   OrganizationsResult,
   PasskeyLoginData,
   PasskeyMetadata,
diff --git a/tests/createSeamlessAuthClient.test.ts b/tests/createSeamlessAuthClient.test.ts
index f82b65c..2990731 100644
--- a/tests/createSeamlessAuthClient.test.ts
+++ b/tests/createSeamlessAuthClient.test.ts
@@ -196,6 +196,31 @@ describe('createSeamlessAuthClient', () => {
     );
   });
 
+  it('surfaces the declared shapes for organization member mutations', async () => {
+    const membership = { userId: 'u1', roles: ['member'] };
+
+    mockFetchWithAuth
+      .mockResolvedValueOnce({ ok: true, json: async () => ({ membership }) })
+      .mockResolvedValueOnce({ ok: true, json: async () => ({ membership }) })
+      .mockResolvedValueOnce({ ok: true, json: async () => ({ message: 'Success' }) });
+
+    const client = createSeamlessAuthClient({
+      apiHost: 'https://api.example.com',
+    });
+
+    // The API returns a single membership envelope for add and update, and a
+    // plain message for remove, not a members list.
+    const added = await client.addOrganizationMember('org-1', { userId: 'u1' });
+    const updated = await client.updateOrganizationMember('org-1', 'u1', {
+      roles: ['admin'],
+    });
+    const removed = await client.removeOrganizationMember('org-1', 'u1');
+
+    expect(added.data?.membership).toEqual(membership);
+    expect(updated.data?.membership).toEqual(membership);
+    expect(removed.data?.message).toBe('Success');
+  });
+
   it('uses OAuth login endpoints', async () => {
     const providersResult = {
       providers: [{ id: 'google', name: 'Google', scopes: ['openid', 'email'] }],