diff --git a/xblock/fields.py b/xblock/fields.py
index 3cad35a..a44afd3 100644
--- a/xblock/fields.py
+++ b/xblock/fields.py
@@ -25,7 +25,7 @@
 __all__ = [
     'BlockScope', 'UserScope', 'Scope', 'ScopeIds',
     'Field',
-    'Boolean', 'Dict', 'Float', 'Integer', 'List', 'String',
+    'Boolean', 'Dict', 'Float', 'Integer', 'List', 'Set', 'String',
     'XBlockMixin',
 ]
 
@@ -770,6 +770,34 @@ def from_json(self, value):
     enforce_type = from_json
 
 
+class Set(JSONField):
+    """
+    A field class for representing a set.
+
+    The stored value can either be None or a set.
+
+    """
+    _default = set()
+
+    def __init__(self, *args, **kwargs):
+        """
+        Set class constructor.
+
+        Redefined in order to convert default values to sets.
+        """
+        super(Set, self).__init__(*args, **kwargs)
+
+        self._default = set(self._default)
+
+    def from_json(self, value):
+        if value is None or isinstance(value, set):
+            return value
+        else:
+            return set(value)
+
+    enforce_type = from_json
+
+
 class String(JSONField):
     """
     A field class for representing a string.
diff --git a/xblock/test/test_core.py b/xblock/test/test_core.py
index 08dc056..163ef84 100644
--- a/xblock/test/test_core.py
+++ b/xblock/test/test_core.py
@@ -23,7 +23,7 @@
     DisallowedFileError,
     FieldDataDeprecationWarning,
 )
-from xblock.fields import Dict, Float, Integer, List, Field, Scope, ScopeIds
+from xblock.fields import Dict, Float, Integer, List, Set, Field, Scope, ScopeIds
 from xblock.field_data import FieldData, DictFieldData
 from xblock.mixins import ScopedStorageMixin
 from xblock.runtime import Runtime
@@ -145,6 +145,59 @@ class FieldTester(XBlock):
     assert_equals([1], field_data.get(field_tester, 'field_d'))
 
 
+def test_set_field_access():
+    # Check that sets are correctly saved when not directly set
+    class FieldTester(XBlock):
+        """Test XBlock for field access testing"""
+        field_a = Set(scope=Scope.settings)
+        field_b = Set(scope=Scope.content, default=[1, 2, 3])
+        field_c = Set(scope=Scope.content, default=[4, 5, 6])
+        field_d = Set(scope=Scope.settings)
+
+    field_tester = FieldTester(MagicMock(), DictFieldData({'field_a': [200], 'field_b': [11, 12, 13]}), Mock())
+
+    # Check initial values have been set properly
+    assert_equals(set([200]), field_tester.field_a)
+    assert_equals(set([11, 12, 13]), field_tester.field_b)
+    assert_equals(set([4, 5, 6]), field_tester.field_c)
+    assert_equals(set(), field_tester.field_d)
+
+    # Update the fields
+    field_tester.field_a.add(1)
+    field_tester.field_b.add(14)
+    field_tester.field_c.remove(5)
+    field_tester.field_d.add(1)
+
+    # The fields should be update in the cache, but /not/ in the underlying kvstore.
+    assert_equals(set([200, 1]), field_tester.field_a)
+    assert_equals(set([11, 12, 13, 14]), field_tester.field_b)
+    assert_equals(set([4, 6]), field_tester.field_c)
+    assert_equals(set([1]), field_tester.field_d)
+
+    # Examine model data directly
+    #  Caveat: there's not a clean way to copy the originally provided values for `field_a` and `field_b`
+    #  when we instantiate the XBlock. So, the values for those two in both `_field_data` and `_field_data_cache`
+    #  point at the same object. Thus, `field_a` and `field_b` actually have the correct values in
+    #  `_field_data` right now. `field_c` does not, because it has never been written to the `_field_data`.
+    assert_false(field_tester._field_data.has(field_tester, 'field_c'))
+    assert_false(field_tester._field_data.has(field_tester, 'field_d'))
+
+    # save the XBlock
+    field_tester.save()
+
+    # verify that the fields have been updated correctly
+    assert_equals(set([200, 1]), field_tester.field_a)
+    assert_equals(set([11, 12, 13, 14]), field_tester.field_b)
+    assert_equals(set([4, 6]), field_tester.field_c)
+    assert_equals(set([1]), field_tester.field_d)
+    # Now, the fields should be updated in the underlying kvstore
+
+    assert_equals(set([200, 1]), field_tester._field_data.get(field_tester, 'field_a'))
+    assert_equals(set([11, 12, 13, 14]), field_tester._field_data.get(field_tester, 'field_b'))
+    assert_equals(set([4, 6]), field_tester._field_data.get(field_tester, 'field_c'))
+    assert_equals(set([1]), field_tester._field_data.get(field_tester, 'field_d'))
+
+
 def test_mutable_none_values():
     # Check that fields with values intentionally set to None
     # save properly.
diff --git a/xblock/test/test_fields.py b/xblock/test/test_fields.py
index 794d592..67d0a46 100644
--- a/xblock/test/test_fields.py
+++ b/xblock/test/test_fields.py
@@ -22,7 +22,7 @@
 from xblock.field_data import DictFieldData
 from xblock.fields import (
     Any, Boolean, Dict, Field, Float,
-    Integer, List, String, DateTime, Reference, ReferenceList, Sentinel,
+    Integer, List, Set, String, DateTime, Reference, ReferenceList, Sentinel,
     UNIQUE_ID
 )
 
@@ -326,6 +326,33 @@ def test_error(self):
         self.assertJSONOrSetTypeError({})
 
 
+class SetTest(FieldTest):
+    """
+    Tests the Set Field.
+    """
+    FIELD_TO_TEST = Set
+
+    def test_json_equals(self):
+        self.assertJSONOrSetEquals(set(), set())
+        self.assertJSONOrSetEquals(set(['foo', 'bar']), set(['foo', 'bar']))
+        self.assertJSONOrSetEquals(set(['bar', 'foo']), set(['foo', 'bar']))
+        self.assertJSONOrSetEquals(set([1, 3.14]), set([1, 3.14]))
+        self.assertJSONOrSetEquals(set([1, 3.14]), set([1, 3.14, 1]))
+
+    def test_hashable_converts(self):
+        self.assertJSONOrSetEquals(set([1, 3.4]), [1, 3.4])
+        self.assertJSONOrSetEquals(set(['a', 'b']), 'ab')
+        self.assertJSONOrSetEquals(set(['k1', 'k2']), {'k1': 1, 'k2': '2'})
+
+    def test_none(self):
+        self.assertJSONOrSetEquals(None, None)
+
+    def test_error(self):
+        self.assertJSONOrSetTypeError(42)
+        self.assertJSONOrSetTypeError(3.7)
+        self.assertJSONOrSetTypeError(True)
+
+
 class ReferenceTest(FieldTest):
     """
     Tests the Reference Field.