diff --git a/config/graphql/mutations.py b/config/graphql/mutations.py
index 2340c1aa..a19135e6 100644
--- a/config/graphql/mutations.py
+++ b/config/graphql/mutations.py
@@ -11,6 +11,7 @@
 from django.db import transaction
 from django.db.models import Q
 from django.utils import timezone
+from filetype import filetype
 from graphene.types.generic import GenericScalar
 from graphql import GraphQLError
 from graphql_jwt.decorators import login_required, user_passes_test
@@ -844,9 +845,23 @@ def mutate(
             )
 
         try:
+            file_bytes = base64.b64decode(base64_file_string)
+
+            # Check file type
+            kind = filetype.guess(file_bytes)
+            if kind is None:
+                return UploadDocument(
+                    message="Unable to determine file type", ok=False, document=None
+                )
+
+            if kind.mime not in settings.ALLOWED_DOCUMENT_MIMETYPES:
+                return UploadDocument(
+                    message=f"Unallowed filetype: {kind.mime}", ok=False, document=None
+                )
+
             user = info.context.user
-            pdf_file = ContentFile(base64.b64decode(base64_file_string), name=filename)
-            document = Document.objects.create(
+            pdf_file = ContentFile(file_bytes, name=filename)
+            document = Document(
                 creator=user,
                 title=title,
                 description=description,
@@ -854,6 +869,7 @@ def mutate(
                 pdf_file=pdf_file,
                 backend_lock=True,
             )
+            document.save()
             set_permissions_for_obj_to_user(user, document, [PermissionTypes.CRUD])
             ok = True
             message = "Success"
diff --git a/config/settings/base.py b/config/settings/base.py
index e229dd62..d59c379f 100644
--- a/config/settings/base.py
+++ b/config/settings/base.py
@@ -116,6 +116,7 @@
 MIGRATION_MODULES = {"sites": "opencontractserver.contrib.sites.migrations"}
 
 # USER LIMITS (FOR USERS WITH IS_USAGE_CAPPED=True)
+# ------------------------------------------------------------------------------
 USAGE_CAPPED_USER_DOC_CAP_COUNT = env.int(
     "USAGE_CAPPED_USER_CORPUS_CAP_COUNT", default=10
 )
@@ -129,6 +130,10 @@
     "USAGE_CAPPED_USER_CAN_EXPORT_CORPUS", default=True
 )
 
+# UPLOAD CONTROLS
+# ------------------------------------------------------------------------------
+ALLOWED_DOCUMENT_MIMETYPES = ["application/pdf"]
+
 # AUTHENTICATION
 # ------------------------------------------------------------------------------
 # https://docs.djangoproject.com/en/dev/ref/settings/#authentication-backends
diff --git a/opencontractserver/tests/test_document_uploads.py b/opencontractserver/tests/test_document_uploads.py
new file mode 100644
index 00000000..362c8892
--- /dev/null
+++ b/opencontractserver/tests/test_document_uploads.py
@@ -0,0 +1,119 @@
+import io
+from unittest.mock import patch
+
+from django.contrib.auth import get_user_model
+from django.test import TestCase
+from docx import Document
+from graphene.test import Client
+
+from config.graphql.schema import schema
+from opencontractserver.utils.pdf import base_64_encode_bytes
+
+User = get_user_model()
+
+
+class TestContext:
+    def __init__(self, user):
+        self.user = user
+
+
+class UploadDocumentMutationTestCase(TestCase):
+    def setUp(self):
+        self.user = User.objects.create_user(
+            username="testuser", password="testpassword"
+        )
+        self.client = Client(schema, context_value=TestContext(self.user))
+
+    def test_upload_document_mime_type_check(self):
+        mutation = """
+            mutation UploadDocument($file: String!, $filename: String!, $title: String!, $description: String!, $customMeta: GenericScalar!) {
+                uploadDocument(
+                    base64FileString: $file,
+                    filename: $filename,
+                    title: $title,
+                    description: $description,
+                    customMeta: $customMeta
+                ) {
+                    ok
+                    message
+                    document {
+                        id
+                        title
+                    }
+                }
+            }
+        """  # noqa
+
+        # Mock file content
+        pdf_content = b"%PDF-1.5\n%\xe2\xe3\xcf\xd3\n"
+
+        # Generate DOCX content
+        docx_buffer = io.BytesIO()
+        doc = Document()
+        doc.add_paragraph("This is a test DOCX file.")
+        doc.save(docx_buffer)
+        docx_content = docx_buffer.getvalue()
+
+        txt_content = b"This is a text file."
+
+        # Encode file content
+        pdf_base64 = base_64_encode_bytes(pdf_content)
+        docx_base64 = base_64_encode_bytes(docx_content)
+        txt_base64 = base_64_encode_bytes(txt_content)
+
+        # Test PDF upload (should succeed)
+        with patch(
+            "opencontractserver.documents.models.Document.objects.create"
+        ) as mock_create:
+            mock_create.return_value = None
+            result = self.client.execute(
+                mutation,
+                variables={
+                    "file": pdf_base64,
+                    "filename": "test.pdf",
+                    "title": "Test PDF",
+                    "description": "A test PDF file",
+                    "customMeta": {},
+                },
+            )
+
+        self.assertIsNone(result.get("errors"))
+        self.assertTrue(result["data"]["uploadDocument"]["ok"])
+        self.assertEqual(result["data"]["uploadDocument"]["message"], "Success")
+
+        # Test DOCX upload (should fail)
+        result = self.client.execute(
+            mutation,
+            variables={
+                "file": docx_base64,
+                "filename": "test.docx",
+                "title": "Test DOCX",
+                "description": "A test DOCX file",
+                "customMeta": {},
+            },
+        )
+
+        self.assertIsNone(result.get("errors"))
+        self.assertFalse(result["data"]["uploadDocument"]["ok"])
+        self.assertEqual(
+            result["data"]["uploadDocument"]["message"],
+            "Unallowed filetype: application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+        )
+
+        # Test TXT upload (should fail)
+        result = self.client.execute(
+            mutation,
+            variables={
+                "file": txt_base64,
+                "filename": "test.txt",
+                "title": "Test TXT",
+                "description": "A test TXT file",
+                "customMeta": {},
+            },
+        )
+
+        self.assertIsNone(result.get("errors"))
+        self.assertFalse(result["data"]["uploadDocument"]["ok"])
+        self.assertEqual(
+            result["data"]["uploadDocument"]["message"], "Unable to determine file type"
+        )
diff --git a/requirements/base.txt b/requirements/base.txt
index 10ca5be3..b5b451f6 100644
--- a/requirements/base.txt
+++ b/requirements/base.txt
@@ -39,7 +39,7 @@ drf-extra-fields==3.4.1  # https://github.com/Hipo/drf-extra-fields
 # ------------------------------------------------------------------------------
 # Pawls preprocessors are available as a command line utility in their repo for now
 # BUT we can install them from their github repo subdirectory using the syntax below:
-git+https://github.com/JSv4/PDF-Preprocessors@v1.0.5
+git+https://github.com/JSv4/PDF-Preprocessors@v1.0.5  # TODO - DEPRECATED. REMOVE.
 scikit-learn
 pdfplumber
 pytesseract
@@ -64,6 +64,7 @@ marvin==2.3.4
 # Data Processing Tools
 # -------------------------------------------------------------------------------
 opencv-python==4.7.0.68 # https://github.com/opencv/opencv-python
+filetype==1.2.0  # https://github.com/h2non/filetype.py
 
 # Permissioning
 # ------------------------------------------------------------------------------
diff --git a/requirements/local.txt b/requirements/local.txt
index 302e1554..75ee3b9c 100644
--- a/requirements/local.txt
+++ b/requirements/local.txt
@@ -47,3 +47,7 @@ pytest-django==4.5.2  # https://github.com/pytest-dev/pytest-django
 # PDFs
 # ------------------------------------------------------------------------------
 pypdf
+
+# Docx
+# ------------------------------------------------------------------------------
+python-docx