diff --git a/README.md b/README.md
index 9bb5921..49c496d 100644
--- a/README.md
+++ b/README.md
@@ -326,6 +326,25 @@ A JWT template reads the same fact as `user.identities` — a provider→`idp_id
 provider the user has not linked, so `{{ user.identities.GoogleOAuth }}` renders the id and an
 unlinked provider renders a claim the emulator drops.
 
+### Seeded MFA factors
+
+Set `totp: true` on a user to enroll a TOTP authentication factor at boot, exactly as
+`POST /user_management/users/{id}/auth_factors` would:
+
+```yaml
+users:
+  - email: alice@acme.com
+    password: test123
+    email_verified: true
+    totp: true # enrolls a TOTP factor; password sign-ins answer with mfa_challenge
+```
+
+The factor is reported by `GET /user_management/users/{id}/auth_factors`, and a password
+sign-in for the user returns the spec's `mfa_challenge` step (a `pending_authentication_token`
+plus an `authentication_challenge`) instead of a session, completed with the
+`urn:workos:oauth:grant-type:mfa-totp` grant — so MFA administration and step-up login flows
+need no post-boot enrollment calls that in-memory state would lose on restart.
+
 ### Pipes connected accounts
 
 `GET|POST|PUT|DELETE /user_management/users/{id}/connected_accounts/{slug}` serve a user's
diff --git a/src/workos/config-validator.ts b/src/workos/config-validator.ts
index 93dedd9..23704dc 100644
--- a/src/workos/config-validator.ts
+++ b/src/workos/config-validator.ts
@@ -120,6 +120,16 @@ export function validateSeedConfig(config: WorkOSSeedConfig): ConfigValidationRe
             value: user.oauth_idp_id,
           });
         }
+        // The YAML 1.2 parser the CLI uses reads `totp: yes` as the string "yes", not a boolean —
+        // and `totp: no` as the equally truthy string "no", which the seed's truthiness check
+        // would silently enroll a factor from, against what the config explicitly declined.
+        if (user.totp !== undefined && typeof user.totp !== 'boolean') {
+          errors.push({
+            path: `users[${index}].totp`,
+            message: 'totp must be a boolean if provided',
+            value: user.totp,
+          });
+        }
       });
 
       // Email is the lookup key org memberships join on; duplicates would silently
diff --git a/src/workos/index.ts b/src/workos/index.ts
index 5467e34..f47899a 100644
--- a/src/workos/index.ts
+++ b/src/workos/index.ts
@@ -152,6 +152,15 @@ export interface WorkOSSeedUser {
    * `oauth_provider` — there is no identity to put it on.
    */
   oauth_idp_id?: string;
+  /**
+   * Enroll a TOTP authentication factor for this user at boot, exactly as
+   * `POST /user_management/users/{id}/auth_factors` would. The factor is reported by
+   * `GET /user_management/users/{id}/auth_factors`, and a password sign-in answers with the
+   * spec's `mfa_challenge` step instead of a session — so MFA administration and step-up
+   * login flows are testable without post-boot enrollment calls that in-memory state loses
+   * on restart.
+   */
+  totp?: boolean;
 }
 
 export interface WorkOSSeedConnection {
@@ -359,6 +368,24 @@ export function seedFromConfig(store: Store, _baseUrl: string, config: WorkOSSee
           userConfig.oauth_idp_id ?? `idp_${generateId('usr')}`,
         );
       }
+
+      // The same record the enrollment route writes, so ListAuthFactors reports it and the
+      // password grant challenges it like any enrolled second factor. The secret surfaces only
+      // inside the URI, as enrollment leaves it.
+      if (userConfig.totp) {
+        const issuer = 'WorkOS Emulator';
+        const secret = randomBytes(20).toString('hex').slice(0, 32).toUpperCase();
+        ws.authFactors.insert({
+          object: 'authentication_factor',
+          user_id: user.id,
+          type: 'totp',
+          totp: {
+            issuer,
+            user: user.email,
+            uri: `otpauth://totp/${encodeURIComponent(issuer)}:${encodeURIComponent(user.email)}?secret=${secret}&issuer=${encodeURIComponent(issuer)}`,
+          },
+        });
+      }
     }
   }
 
diff --git a/src/workos/seed-auth-factors.spec.ts b/src/workos/seed-auth-factors.spec.ts
new file mode 100644
index 0000000..1e39096
--- /dev/null
+++ b/src/workos/seed-auth-factors.spec.ts
@@ -0,0 +1,116 @@
+/**
+ * Seeding TOTP authentication factors. Every other authentication method a user can hold is
+ * seedable (`password`, `oauth_provider`), and with in-memory state a factor enrolled over
+ * HTTP after boot does not survive a restart while the seeded users do. `totp: true` writes
+ * the same record `POST /user_management/users/{id}/auth_factors` writes, so ListAuthFactors
+ * reports it and a password sign-in walks the spec's `mfa_challenge` step-up — no post-boot
+ * enrollment calls.
+ */
+import { describe, it, expect, afterEach } from 'bun:test';
+import { createEmulator, type Emulator } from '../index.js';
+import { getWorkOSStore } from './store.js';
+import { validateSeedConfig } from './config-validator.js';
+
+const PINNED_USER_ID = 'user_01SEEDTOTP0000000000000000';
+
+describe('Seeding TOTP authentication factors', () => {
+  let emulator: Emulator | undefined;
+
+  afterEach(async () => {
+    await emulator?.close();
+    emulator = undefined;
+  });
+
+  const auth = (apiKey: string) => ({ Authorization: `Bearer ${apiKey}`, 'Content-Type': 'application/json' });
+
+  it("reports the seeded factor with the enrollment route's shape", async () => {
+    emulator = await createEmulator({
+      port: 0,
+      seed: {
+        users: [{ id: PINNED_USER_ID, email: 'alice@acme.com', password: 'test123', totp: true }],
+      },
+    });
+
+    const res = await fetch(`${emulator.url}/user_management/users/${PINNED_USER_ID}/auth_factors`, {
+      headers: auth(emulator.apiKey),
+    });
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as any;
+    expect(body.object).toBe('list');
+    expect(body.data).toHaveLength(1);
+
+    const factor = body.data[0];
+    expect(factor.object).toBe('authentication_factor');
+    expect(factor.id).toMatch(/^auth_factor_/);
+    expect(factor.type).toBe('totp');
+    expect(factor.totp.issuer).toBe('WorkOS Emulator');
+    expect(factor.totp.user).toBe('alice@acme.com');
+    expect(factor.totp.uri).toStartWith('otpauth://totp/');
+  });
+
+  it('drives the password grant through the mfa_challenge step-up', async () => {
+    emulator = await createEmulator({
+      port: 0,
+      seed: {
+        users: [{ email: 'mfa@acme.com', password: 'test123', email_verified: true, totp: true }],
+      },
+    });
+
+    // The seeded factor is an enrolled second factor: no session until it clears.
+    const passwordRes = await fetch(`${emulator.url}/user_management/authenticate`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ grant_type: 'password', email: 'mfa@acme.com', password: 'test123' }),
+    });
+    expect(passwordRes.status).toBe(403);
+    const challengeBody = (await passwordRes.json()) as any;
+    expect(challengeBody.code).toBe('mfa_challenge');
+
+    // The response withholds the one-time code, as production does; read it off the challenge.
+    const ws = getWorkOSStore(emulator.store);
+    const challengeCode = ws.authChallenges.get(challengeBody.authentication_challenge.id)!.code;
+
+    const mfaRes = await fetch(`${emulator.url}/user_management/authenticate`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({
+        grant_type: 'urn:workos:oauth:grant-type:mfa-totp',
+        code: challengeCode,
+        pending_authentication_token: challengeBody.pending_authentication_token,
+        authentication_challenge_id: challengeBody.authentication_challenge.id,
+      }),
+    });
+    expect(mfaRes.status).toBe(200);
+    const session = (await mfaRes.json()) as any;
+    expect(session.user.email).toBe('mfa@acme.com');
+    // The session reports the primary factor the pending token recorded.
+    expect(session.authentication_method).toBe('Password');
+  });
+
+  it('does not enroll a factor for users the seed left alone', async () => {
+    emulator = await createEmulator({
+      port: 0,
+      seed: {
+        users: [
+          { id: PINNED_USER_ID, email: 'plain@acme.com', password: 'test123' },
+          { email: 'enrolled@acme.com', totp: true },
+        ],
+      },
+    });
+
+    const res = await fetch(`${emulator.url}/user_management/users/${PINNED_USER_ID}/auth_factors`, {
+      headers: auth(emulator.apiKey),
+    });
+    const body = (await res.json()) as any;
+    expect(body.data).toEqual([]);
+  });
+
+  it('accepts a boolean totp and rejects anything else', () => {
+    const ok = validateSeedConfig({ users: [{ email: 'a@b.co', totp: true }] });
+    expect(ok.valid).toBe(true);
+
+    const bad = validateSeedConfig({ users: [{ email: 'a@b.co', totp: 'yes' as unknown as boolean }] });
+    expect(bad.valid).toBe(false);
+    expect(bad.errors[0].path).toBe('users[0].totp');
+  });
+});