diff --git a/cleancat/base.py b/cleancat/base.py
index 6cd7ab0..c85bf2b 100644
--- a/cleancat/base.py
+++ b/cleancat/base.py
@@ -231,7 +231,8 @@ class List(Field):
     base_type = list
     blank_value = []
 
-    def __init__(self, field_instance, **kwargs):
+    def __init__(self, field_instance, max_length=None, **kwargs):
+        self.max_length = max_length
         super(List, self).__init__(**kwargs)
         self.field_instance = field_instance
 
@@ -240,9 +241,14 @@ def has_value(self, value):
 
     def clean(self, value):
         value = super(List, self).clean(value)
-        if self.required and not len(value):
+
+        item_cnt = len(value)
+        if self.required and not item_cnt:
             raise ValidationError('List must not be empty.')
 
+        if self.max_length and item_cnt > self.max_length:
+            raise ValidationError('List is too long.')
+
         errors = {}
         data = []
         for n, item in enumerate(value):
diff --git a/tests/__init__.py b/tests/__init__.py
index e6a60de..0ea202a 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -223,6 +223,9 @@ class TagsSchema(Schema):
         class OptionalTagsSchema(Schema):
             tags = List(String(), required=False)
 
+        class SmallTagsSchema(Schema):
+            tags = List(String(), max_length=2)
+
         self.assertValid(TagsSchema({'tags': ['python', 'ruby']}), {'tags': ['python', 'ruby']})
         self.assertInvalid(TagsSchema({'tags': []}), {'field-errors': ['tags']})
         self.assertInvalid(TagsSchema({'tags': None}), {'field-errors': ['tags']})
@@ -233,6 +236,10 @@ class OptionalTagsSchema(Schema):
         self.assertValid(OptionalTagsSchema({'tags': None}), {'tags': []})
         self.assertValid(OptionalTagsSchema({}), {'tags': []})
 
+        self.assertValid(SmallTagsSchema({'tags': ['python', 'ruby']}), {'tags': ['python', 'ruby']})
+        self.assertInvalid(SmallTagsSchema({'tags': []}), {'field-errors': ['tags']})
+        self.assertInvalid(SmallTagsSchema({'tags': ['python', 'ruby', 'go']}), {'field-errors': ['tags']})
+
     def test_choice(self):
         class ChoiceSchema(Schema):
             choice = Choices(choices=['Hello', 'world'])