diff --git a/cumulus_library/apis/umls.py b/cumulus_library/apis/umls.py
index b6592b6e..74f778ec 100644
--- a/cumulus_library/apis/umls.py
+++ b/cumulus_library/apis/umls.py
@@ -57,7 +57,11 @@ def __init__(self, api_key: str | None = None, validator_key: str | None = None)
         self.session.auth = requests.auth.HTTPBasicAuth("apikey", api_key)
 
     def get_vsac_valuesets(
-        self, url: str | None = None, oid: str | None = None, action: str = "expansion"
+        self,
+        url: str | None = None,
+        oid: str | None = None,
+        action: str = "expansion",
+        offset: int = 0,
     ) -> list[dict]:
         """Gets a valueset, and any nested valuesets, from the VSAC API
 
@@ -82,7 +86,7 @@ def get_vsac_valuesets(
         if oid:
             url = f"{url}/{oid}"
         # TODO: Do we need to support the remaining FHIR operators?
-        if action == "expansion":
+        if action == "expansion" and "/$expand" not in url:
             url = url + "/$expand"
         # If we're inspecting url references in a VSAC response, they come back
         # specifying a url that does not align with the actual implemented rest
@@ -91,16 +95,32 @@ def get_vsac_valuesets(
             url = url.replace("http:", "https:")
         if "/res/" not in url:
             url = url.replace("/fhir/", "/fhir/res/")
-        response = self.session.get(url)
+        match action:
+            case "definition":
+                response = self.session.get(url)
+            case "expansion":
+                response = self.session.get(url + f"?offset={offset}")
         if response.status_code == 404:
             raise errors.ApiError(f"Url not found: {url}")
         all_responses = [response.json()]
+        if action == "expansion":
+            # Do we need to fetch the next page?
+            # Note: the VSAC API hard codes the page size to 1000
+            # and ignores the count param in the FHIR ValueSet expand API
+            # (https://www.hl7.org/fhir/ValueSet-operation-expand.html),
+            # so we just hardcode an expansion of 1000 and hope it
+            # doesn't change
+            if all_responses[0]["expansion"]["total"] > offset + 1000:
+                all_responses += self.get_vsac_valuesets(
+                    action=action, url=url, offset=offset + 1000
+                )
         if action == "definition":
             included_records = all_responses[0].get("compose", {}).get("include", [])
             for record in included_records:
                 if "valueSet" in record:
                     valueset = self.get_vsac_valuesets(action=action, url=record["valueSet"][0])
                     all_responses.append(valueset[0])
+
         return all_responses
 
     def get_latest_umls_file_release(self, target: str):
diff --git a/tests/test_data/apis/umls/expansion_valueset.json b/tests/test_data/apis/umls/expansion_valueset.json
index f17321c6..d6731e33 100644
--- a/tests/test_data/apis/umls/expansion_valueset.json
+++ b/tests/test_data/apis/umls/expansion_valueset.json
@@ -25,7 +25,7 @@
   "expansion": {
     "identifier": "urn:uuid:a0298877-7908-4db0-a19f-449c857b3c44",
     "timestamp": "2024-07-25T14:55:42-04:00",
-    "total": 836,
+    "total": 1001,
     "offset": 0,
     "parameter": [ {
       "name": "count",
diff --git a/tests/test_umls_api.py b/tests/test_umls_api.py
index e458d148..99c8a30f 100644
--- a/tests/test_umls_api.py
+++ b/tests/test_umls_api.py
@@ -116,7 +116,7 @@ def get_valueset_data(file_name):
             "expansion",
             VALUESET_URL + "/" + EXPANSION_VALUESET_OID,
             None,
-            [EXPANSION_VALUESET_OID],
+            [EXPANSION_VALUESET_OID, EXPANSION_VALUESET_OID],
             does_not_raise(),
         ),
         ("definition", None, None, [], pytest.raises(errors.ApiError)),
@@ -142,7 +142,13 @@ def test_get_valueset(action, url, oid, expected_oids, raises):
         )
         responses.add(
             responses.GET,
-            VALUESET_URL + "/" + EXPANSION_VALUESET_OID + "/$expand",
+            VALUESET_URL + "/" + EXPANSION_VALUESET_OID + "/$expand?offset=0",
+            body=get_valueset_data("expansion_valueset.json"),
+            status=200,
+        )
+        responses.add(
+            responses.GET,
+            VALUESET_URL + "/" + EXPANSION_VALUESET_OID + "/$expand?offset=1000",
             body=get_valueset_data("expansion_valueset.json"),
             status=200,
         )