diff --git a/src/gradescopeapi/classes/_helpers/_assignment_helpers.py b/src/gradescopeapi/classes/_helpers/_assignment_helpers.py
index aa85e23..a909b88 100644
--- a/src/gradescopeapi/classes/_helpers/_assignment_helpers.py
+++ b/src/gradescopeapi/classes/_helpers/_assignment_helpers.py
@@ -179,15 +179,28 @@ def get_submission_files(
         f"{gradescope_base_url}/courses/{course_id}/assignments/{assignment_id}"
     )
 
-    file_info_link = f"{ASSIGNMENT_ENDPOINT}/submissions/{submission_id}.json?content=react&only_keys[]=text_files&only_keys[]=file_comments"
+    file_info_link = (
+        f"{ASSIGNMENT_ENDPOINT}/submissions/{submission_id}.json?content=react"
+        "&only_keys[]=text_files&only_keys[]=file_comments"
+        "&only_keys[]=pdf_attachment&only_keys[]=image_attachments"
+    )
     file_info_resp = session.get(file_info_link)
+    aws_links = []
     if file_info_resp.status_code == requests.codes.ok:
         file_info_json = json.loads(file_info_resp.text)
         if file_info_json.get("text_files"):
-            aws_links = []
+            # autograder / code submissions
             for file_data in file_info_json["text_files"]:
                 aws_links.append(file_data["file"]["url"])
+        elif file_info_json.get("pdf_attachment", {}).get("url"):
+            # PDF / image submissions: Gradescope stores the student's original
+            # upload as a single combined pdf_attachment (the un-annotated file).
+            aws_links.append(file_info_json["pdf_attachment"]["url"])
+        elif file_info_json.get("image_attachments"):
+            # fallback: individual image files when there is no combined PDF
+            for image in file_info_json["image_attachments"]:
+                if image.get("url"):
+                    aws_links.append(image["url"])
         else:
-            raise NotImplementedError("Image only submissions not yet supported")
-        # TODO add support for image questions
+            raise NotImplementedError("Submission has no downloadable files")
     return aws_links
diff --git a/tests/test_submission_files_unit.py b/tests/test_submission_files_unit.py
new file mode 100644
index 0000000..b304fba
--- /dev/null
+++ b/tests/test_submission_files_unit.py
@@ -0,0 +1,62 @@
+"""Unit tests for get_submission_files — no network/credentials required.
+
+A fake session returns a canned submission JSON so we can exercise each
+submission shape (autograder text_files, PDF/image submissions via
+pdf_attachment, and image_attachments).
+"""
+import json
+
+import pytest
+
+from gradescopeapi.classes._helpers._assignment_helpers import get_submission_files
+
+
+class _FakeResp:
+    status_code = 200
+
+    def __init__(self, payload):
+        self.text = json.dumps(payload)
+
+
+class _FakeSession:
+    def __init__(self, payload):
+        self._payload = payload
+
+    def get(self, url):
+        return _FakeResp(self._payload)
+
+
+def _call(payload):
+    return get_submission_files(_FakeSession(payload), "1", "2", "3")
+
+
+def test_text_files_submission():
+    links = _call({"text_files": [{"file": {"url": "https://aws/a.py"}}]})
+    assert links == ["https://aws/a.py"]
+
+
+def test_pdf_attachment_submission():
+    # PDF/image submission: no autograder text_files, just a combined PDF
+    links = _call(
+        {"text_files": [], "pdf_attachment": {"url": "https://aws/orig.pdf"}}
+    )
+    assert links == ["https://aws/orig.pdf"]
+
+
+def test_image_attachments_submission():
+    links = _call(
+        {
+            "text_files": [],
+            "pdf_attachment": {},
+            "image_attachments": [
+                {"url": "https://aws/1.jpg"},
+                {"url": "https://aws/2.jpg"},
+            ],
+        }
+    )
+    assert links == ["https://aws/1.jpg", "https://aws/2.jpg"]
+
+
+def test_no_files_raises():
+    with pytest.raises(NotImplementedError):
+        _call({"text_files": [], "pdf_attachment": {}, "image_attachments": []})