diff --git a/README.md b/README.md
index 5d24a0b..ec92def 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,7 @@ Add [Laravel Sanctum](https://github.com/laravel/sanctum) support to [Lighthouse
     - [Email Verification](#email-verification)
     - [Forgot Password](#forgot-password)
     - [Reset Password](#reset-password)
+- [Custom Identification](#custom-identification)
 
 ## Requirements
 
@@ -134,6 +135,8 @@ Apply the Authorization header on subsequent calls using the token
   "Authorization": "Bearer 1|lJo1cMhrW9tIUuGwlV1EPjKnvfZKzvgpGgplbwX9"
 ```
 
+(Using something other than email? See [Custom Identification](#custom-identification))
+
 ### Logout
 
 Revoke the current token.
@@ -295,6 +298,33 @@ mutation {
 }
 ```
 
+### Custom Identification
+
+You can customize which fields are used for authenticating users.
+
+For example, using `username` instead of the default `email`.
+```php
+/*
+|--------------------------------------------------------------------------
+| Identification
+|--------------------------------------------------------------------------
+|
+| Configure the credential fields by which the user will be identified.
+| Default: email
+*/
+
+'user_identifier_field_name' => 'username',
+```
+
+Update the GraphQL schema accordingly
+
+```graphql
+input LoginInput {
+    username: String! @rules(apply: ["required"])
+}
+```
+
+
 ## Testing
 
 ```bash
diff --git a/config/lighthouse-sanctum.php b/config/lighthouse-sanctum.php
index 4d4ca3e..a229fc5 100644
--- a/config/lighthouse-sanctum.php
+++ b/config/lighthouse-sanctum.php
@@ -26,4 +26,15 @@
     |
     */
     'use_signed_email_verification_url' => false,
+
+    /*
+    |--------------------------------------------------------------------------
+    | Identification
+    |--------------------------------------------------------------------------
+    |
+    | Configure the credential fields by which the user will be identified.
+    | Default: email
+    */
+
+    'user_identifier_field_name' => 'email',
 ];
diff --git a/src/GraphQL/Mutations/Login.php b/src/GraphQL/Mutations/Login.php
index f9f66af..be862ff 100644
--- a/src/GraphQL/Mutations/Login.php
+++ b/src/GraphQL/Mutations/Login.php
@@ -36,8 +36,11 @@ public function __invoke($_, array $args): array
     {
         $userProvider = $this->createUserProvider();
 
+        $identificationKey = $this->getConfig()
+            ->get('lighthouse-sanctum.identification.user_identifier_field_name', 'email');
+
         $user = $userProvider->retrieveByCredentials([
-            'email'    => $args['email'],
+            $identificationKey => $args[$identificationKey],
             'password' => $args['password'],
         ]);
 
diff --git a/src/Services/ResetPasswordService.php b/src/Services/ResetPasswordService.php
index f8c98bb..fcf76c7 100644
--- a/src/Services/ResetPasswordService.php
+++ b/src/Services/ResetPasswordService.php
@@ -37,7 +37,8 @@ public function transformUrl(CanResetPassword $notifiable, string $token, string
 
     public function setResetPasswordUrl(string $url): void
     {
-        ResetPasswordNotification::createUrlUsing(function (CanResetPassword $notifiable, string $token) use ($url) {
+        /** @phpstan-ignore-next-line */
+        ResetPasswordNotification::createUrlUsing(function (CanResetPassword $notifiable, string $token) use ($url): string {
             return $this->transformUrl($notifiable, $token, $url);
         });
     }
diff --git a/tests/Integration/GraphQL/Mutations/ForgotPasswordTest.php b/tests/Integration/GraphQL/Mutations/ForgotPasswordTest.php
index 7a451a5..a3ca58e 100644
--- a/tests/Integration/GraphQL/Mutations/ForgotPasswordTest.php
+++ b/tests/Integration/GraphQL/Mutations/ForgotPasswordTest.php
@@ -45,6 +45,7 @@ public function it_sends_a_reset_password_notification(): void
         ]);
 
         Notification::assertSentTo($user, function (ResetPassword $notification) use ($user) {
+            /** @phpstan-ignore-next-line */
             $url = call_user_func($notification::$createUrlCallback, $user, $notification->token);
 
             return $url === "https://my-front-end.com/reset-password?email=john.doe@gmail.com&token={$notification->token}";
diff --git a/tests/Integration/Services/ResetPasswordServiceTest.php b/tests/Integration/Services/ResetPasswordServiceTest.php
index baabb01..d04ebff 100644
--- a/tests/Integration/Services/ResetPasswordServiceTest.php
+++ b/tests/Integration/Services/ResetPasswordServiceTest.php
@@ -61,6 +61,7 @@ public function it_sets_the_reset_password_url(): void
 
         $this->service->setResetPasswordUrl('https://mysite.com/reset-password/__EMAIL__/__TOKEN__');
 
+        /** @phpstan-ignore-next-line */
         $url = call_user_func(ResetPassword::$createUrlCallback, $user, $token);
 
         static::assertSame('https://mysite.com/reset-password/user@example.com/token123', $url);
diff --git a/tests/Traits/MocksUserProvider.php b/tests/Traits/MocksUserProvider.php
index 40dc66a..b609b0d 100644
--- a/tests/Traits/MocksUserProvider.php
+++ b/tests/Traits/MocksUserProvider.php
@@ -38,7 +38,12 @@ protected function mockConfig()
             ->shouldReceive('get')
             ->with('lighthouse-sanctum.provider')
             ->andReturn('sanctum-provider')
-            ->getMock();
+            ->getMock()
+            ->shouldReceive('get')
+            ->with('lighthouse-sanctum.identification.user_identifier_field_name', 'email')
+            ->andReturn('email')
+            ->getMock()
+        ;
 
         return $config;
     }
diff --git a/tests/Unit/GraphQL/Mutations/LoginTest.php b/tests/Unit/GraphQL/Mutations/LoginTest.php
index 54b05dd..d785f4d 100644
--- a/tests/Unit/GraphQL/Mutations/LoginTest.php
+++ b/tests/Unit/GraphQL/Mutations/LoginTest.php
@@ -11,6 +11,7 @@
 use DanielDeWit\LighthouseSanctum\Tests\Traits\MocksUserProvider;
 use DanielDeWit\LighthouseSanctum\Tests\Unit\AbstractUnitTest;
 use Illuminate\Contracts\Auth\UserProvider;
+use Illuminate\Contracts\Config\Repository as Config;
 use Illuminate\Foundation\Auth\User;
 use Laravel\Sanctum\NewAccessToken;
 use Mockery;
@@ -62,6 +63,64 @@ public function it_logs_a_user_in(): void
         static::assertSame('1234567890', $result['token']);
     }
 
+    /**
+     * @test
+     */
+    public function it_logs_a_user_in_using_custom_identification(): void
+    {
+        /** @var Config|MockInterface $config */
+        $config = Mockery::mock(Config::class)
+            ->shouldReceive('get')
+            ->with('lighthouse-sanctum.provider')
+            ->andReturn('sanctum-provider')
+            ->getMock()
+            ->shouldReceive('get')
+            ->with('lighthouse-sanctum.identification.user_identifier_field_name', 'email')
+            ->andReturn('custom_key')
+            ->getMock();
+
+        $token = Mockery::mock(NewAccessToken::class);
+        $token->plainTextToken = '1234567890';
+
+        /** @var UserHasApiTokens|MockInterface $user */
+        $user = Mockery::mock(UserHasApiTokens::class)
+            ->shouldReceive('createToken')
+            ->with('default')
+            ->andReturn($token)
+            ->getMock();
+
+        /** @var UserProvider|MockInterface $userProvider */
+        $userProvider = Mockery::mock(UserProvider::class)
+            ->shouldReceive('retrieveByCredentials')
+            ->with([
+                'custom_key'  => 'foo@bar.com',
+                'password' => 'supersecret',
+            ])
+            ->andReturn($user)
+            ->getMock()
+            ->shouldReceive('validateCredentials')
+            ->with($user, [
+                'custom_key'  => 'foo@bar.com',
+                'password' => 'supersecret',
+            ])
+            ->andReturnTrue()
+            ->getMock();
+
+        $mutation = new Login(
+            $this->mockAuthManager($userProvider),
+            $config,
+        );
+
+        $result = $mutation(null, [
+            'custom_key'  => 'foo@bar.com',
+            'password' => 'supersecret',
+        ]);
+
+        static::assertIsArray($result);
+        static::assertCount(1, $result);
+        static::assertSame('1234567890', $result['token']);
+    }
+
     /**
      * @test
      */
diff --git a/tests/stubs/Users/UserHasApiTokens.php b/tests/stubs/Users/UserHasApiTokens.php
index 5b1d6b0..9751702 100644
--- a/tests/stubs/Users/UserHasApiTokens.php
+++ b/tests/stubs/Users/UserHasApiTokens.php
@@ -17,10 +17,13 @@ class UserHasApiTokens extends User implements HasApiTokensContract
     use HasFactory;
     use Notifiable;
 
+    /**
+     * @var string
+     */
     protected $table = 'users';
 
     /**
-     * @var string[]
+     * @var array<int, string>
      */
     protected $fillable = [
         'name',
@@ -30,7 +33,7 @@ class UserHasApiTokens extends User implements HasApiTokensContract
     ];
 
     /**
-     * @var string[]
+     * @var array<int, string>
      */
     protected $hidden = [
         'password',