diff --git a/src/Schema/Field/Str.php b/src/Schema/Field/Str.php
index 36f848b..866d400 100644
--- a/src/Schema/Field/Str.php
+++ b/src/Schema/Field/Str.php
@@ -8,6 +8,7 @@ class Str extends Attribute
     public ?int $maxLength = null;
     public ?string $pattern = null;
     public ?string $format = null;
+    public ?array $enum = null;
 
     public function __construct(string $name)
     {
@@ -21,6 +22,11 @@ public function __construct(string $name)
                 return;
             }
 
+            if ($this->enum !== null && !in_array($value, $this->enum, true)) {
+                $enum = array_map(fn ($value) => '"' . $value . '"', $this->enum);
+                $fail(sprintf('must be one of %s', implode(', ', $enum)));
+            }
+
             if (strlen($value) < $this->minLength) {
                 $fail(sprintf('must be at least %d characters', $this->minLength));
             }
@@ -66,6 +72,13 @@ public function format(?string $format): static
         return $this;
     }
 
+    public function enum(?array $enum): static
+    {
+        $this->enum = $enum;
+
+        return $this;
+    }
+
     public function getSchema(): array
     {
         return parent::getSchema() + [
@@ -74,6 +87,7 @@ public function getSchema(): array
             'maxLength' => $this->maxLength,
             'pattern' => $this->pattern,
             'format' => $this->format,
+            'enum' => $this->enum,
         ];
     }
 }
diff --git a/tests/feature/StrTest.php b/tests/feature/StrTest.php
index 0019549..f4f3d1c 100644
--- a/tests/feature/StrTest.php
+++ b/tests/feature/StrTest.php
@@ -57,4 +57,46 @@ public function test_validates_string()
             ]),
         );
     }
+
+    public function test_invalid_enum()
+    {
+        $this->api->resource(
+            new MockResource(
+                'users',
+                endpoints: [Create::make()],
+                fields: [Str::make('type')->writable()->enum(['A', 'B'])],
+            ),
+        );
+
+        $this->expectException(UnprocessableEntityException::class);
+
+        $this->api->handle(
+            $this->buildRequest('POST', '/users')->withParsedBody([
+                'data' => ['type' => 'users', 'attributes' => ['type' => 'C']],
+            ]),
+        );
+    }
+
+    public function test_valid_enum()
+    {
+        $this->api->resource(
+            new MockResource(
+                'users',
+                endpoints: [Create::make()],
+                fields: [Str::make('type')->writable()->enum(['A', 'B'])],
+            ),
+        );
+
+        $response = $this->api->handle(
+            $this->buildRequest('POST', '/users')->withParsedBody([
+                'data' => ['type' => 'users', 'attributes' => ['type' => 'A']],
+            ]),
+        );
+
+        $this->assertJsonApiDocumentSubset(
+            ['data' => ['attributes' => ['type' => 'A']]],
+            $response->getBody(),
+            true,
+        );
+    }
 }