diff --git a/packages/graphrag/graphrag/query/indexer_adapters.py b/packages/graphrag/graphrag/query/indexer_adapters.py
index 7119ad842c..a6ded1f9f7 100644
--- a/packages/graphrag/graphrag/query/indexer_adapters.py
+++ b/packages/graphrag/graphrag/query/indexer_adapters.py
@@ -221,5 +221,5 @@ def _filter_under_community_level(
 ) -> pd.DataFrame:
     return cast(
         "pd.DataFrame",
-        df[df.level <= community_level],
+        df[(df.level <= community_level) | df.level.isna()],
     )
diff --git a/tests/unit/query/test_indexer_adapters.py b/tests/unit/query/test_indexer_adapters.py
new file mode 100644
index 0000000000..182e1e12cf
--- /dev/null
+++ b/tests/unit/query/test_indexer_adapters.py
@@ -0,0 +1,50 @@
+# Copyright (c) 2024 Microsoft Corporation.
+# Licensed under the MIT License
+
+"""Tests for _filter_under_community_level logic."""
+
+import pandas as pd
+
+
+def _filter_under_community_level(
+    df: pd.DataFrame, community_level: int
+) -> pd.DataFrame:
+    return df[(df.level <= community_level) | df.level.isna()]
+
+
+def test_filter_under_community_level_preserves_nan():
+    df = pd.DataFrame(
+        {
+            "id": [1, 2, 3, 4],
+            "level": [0, 1, None, 2],
+            "title": ["a", "b", "c", "d"],
+        }
+    )
+    result = _filter_under_community_level(df, 1)
+    assert len(result) == 3
+    assert result["id"].tolist() == [1, 2, 3]
+
+
+def test_filter_under_community_level_all_assigned():
+    df = pd.DataFrame(
+        {
+            "id": [1, 2, 3],
+            "level": [0, 1, 2],
+            "title": ["a", "b", "c"],
+        }
+    )
+    result = _filter_under_community_level(df, 1)
+    assert len(result) == 2
+    assert result["id"].tolist() == [1, 2]
+
+
+def test_filter_under_community_level_all_nan():
+    df = pd.DataFrame(
+        {
+            "id": [1, 2, 3],
+            "level": [None, None, None],
+            "title": ["a", "b", "c"],
+        }
+    )
+    result = _filter_under_community_level(df, 1)
+    assert len(result) == 3