diff --git a/emannotationschemas/__init__.py b/emannotationschemas/__init__.py
index 56c8343..de8e3be 100644
--- a/emannotationschemas/__init__.py
+++ b/emannotationschemas/__init__.py
@@ -52,7 +52,7 @@
     DigitalTwinPropertiesBCM,
 )
 from emannotationschemas.schemas.glia_contact import GliaContact
-from emannotationschemas.schemas.groups import SimpleGroup
+from emannotationschemas.schemas.groups import SimpleGroup, SimpleGroupIndexed
 from emannotationschemas.schemas.neuropil import FlyNeuropil
 from emannotationschemas.schemas.nucleus_detection import NucleusDetection
 from emannotationschemas.schemas.postsynaptic_compartment import PostsynapticCompartment
@@ -124,6 +124,7 @@
     "representative_point": RepresentativePoint,
     "reference_synapse_valid": ValidSynapse,
     "reference_simple_group": SimpleGroup,
+    "reference_simple_group_indexed": SimpleGroupIndexed,
     "fly_cell_type": FlyCellType,
     "fly_cell_type_ext": FlyCellTypeExt,
     "braincircuits_annotation_user": BrainCircuitsBoundTagAnnotationUser,
diff --git a/emannotationschemas/schemas/groups.py b/emannotationschemas/schemas/groups.py
index 442a4ab..b7bdf11 100644
--- a/emannotationschemas/schemas/groups.py
+++ b/emannotationschemas/schemas/groups.py
@@ -7,3 +7,10 @@ class SimpleGroup(ReferenceAnnotation):
         required=True,
         description="group id",
     )
+
+class SimpleGroupIndexed(ReferenceAnnotation):
+    group_id = mm.fields.Int(
+        required=True,
+        description="group id",
+        index=True,
+    )
diff --git a/tests/test_simple_group.py b/tests/test_simple_group.py
new file mode 100644
index 0000000..51240ab
--- /dev/null
+++ b/tests/test_simple_group.py
@@ -0,0 +1,27 @@
+from emannotationschemas.schemas.groups import SimpleGroup, SimpleGroupIndexed
+
+good_simple_group = {
+    "pt": {"position": [31, 32, 33]},
+    "group_id": 42,
+    "target_id": 456,
+}
+
+good_simple_group_indexed = {
+    "pt": {"position": [10, 20, 30]},
+    "group_id": 123,
+    "target_id": 456,
+}
+
+
+def test_simple_group_schema():
+    schema = SimpleGroup()
+    result = schema.load(good_simple_group)
+    assert result["group_id"] == 42
+    assert result["pt"]["position"] == [31, 32, 33]
+
+
+def test_simple_group_indexed_schema():
+    schema = SimpleGroupIndexed()
+    result = schema.load(good_simple_group_indexed)
+    assert result["group_id"] == 123
+    assert result["pt"]["position"] == [10, 20, 30]