diff --git a/src/docx/__init__.py b/src/docx/__init__.py
index fd06c84d2..3d5f34a15 100644
--- a/src/docx/__init__.py
+++ b/src/docx/__init__.py
@@ -44,6 +44,7 @@ def part_class_selector(content_type: str, reltype: str) -> Type[Part] | None:
 PartFactory.part_type_for[CT.OPC_CORE_PROPERTIES] = CorePropertiesPart
 PartFactory.part_type_for[CT.WML_COMMENTS] = CommentsPart
 PartFactory.part_type_for[CT.WML_DOCUMENT_MAIN] = DocumentPart
+PartFactory.part_type_for[CT.WML_TEMPLATE_MAIN] = DocumentPart
 PartFactory.part_type_for[CT.WML_FOOTER] = FooterPart
 PartFactory.part_type_for[CT.WML_HEADER] = HeaderPart
 PartFactory.part_type_for[CT.WML_NUMBERING] = NumberingPart
diff --git a/src/docx/api.py b/src/docx/api.py
index aea876458..276bc58c0 100644
--- a/src/docx/api.py
+++ b/src/docx/api.py
@@ -25,7 +25,7 @@ def Document(docx: str | IO[bytes] | None = None) -> DocumentObject:
     """
     docx = _default_docx_path() if docx is None else docx
     document_part = cast("DocumentPart", Package.open(docx).main_document_part)
-    if document_part.content_type != CT.WML_DOCUMENT_MAIN:
+    if document_part.content_type not in (CT.WML_DOCUMENT_MAIN, CT.WML_TEMPLATE_MAIN):
         tmpl = "file '%s' is not a Word file, content type is '%s'"
         raise ValueError(tmpl % (docx, document_part.content_type))
     return document_part.document
diff --git a/src/docx/opc/constants.py b/src/docx/opc/constants.py
index a3d0e0812..30b856614 100644
--- a/src/docx/opc/constants.py
+++ b/src/docx/opc/constants.py
@@ -135,6 +135,9 @@ class CONTENT_TYPE:
     WML_DOCUMENT_MAIN = (
         "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml"
     )
+    WML_TEMPLATE_MAIN = (
+    "application/vnd.openxmlformats-officedocument.wordprocessingml.template.main+xml"
+    )
     WML_ENDNOTES = "application/vnd.openxmlformats-officedocument.wordprocessingml.endnotes+xml"
     WML_FONT_TABLE = "application/vnd.openxmlformats-officedocument.wordprocessingml.fontTable+xml"
     WML_FOOTER = "application/vnd.openxmlformats-officedocument.wordprocessingml.footer+xml"
diff --git a/tests/test_dotx_template.py b/tests/test_dotx_template.py
new file mode 100644
index 000000000..14ea32714
--- /dev/null
+++ b/tests/test_dotx_template.py
@@ -0,0 +1,36 @@
+"""Tests for Issue #1532: .dotx template support."""
+
+import os
+
+import pytest
+
+from docx import Document
+from docx.package import Package
+from docx.parts.document import DocumentPart
+
+
+class DescribeDotxTemplate:
+    """Unit-test suite for .dotx file support."""
+
+    def it_can_load_a_dotx_template_file(self):
+        """Test loading a real .dotx file."""
+        template_path = "test_dotx_real.dotx"
+
+        if not os.path.exists(template_path):
+            pytest.skip(f"Template file {template_path} not found")
+
+        # It should load the file successfully
+        doc = Document(template_path)
+        assert doc is not None
+        assert hasattr(doc, "paragraphs")
+
+    def it_creates_document_part_for_dotx_files(self):
+        """Test that .dotx files create DocumentPart, not generic Part."""
+        template_path = "test_dotx_real.dotx"
+
+        if not os.path.exists(template_path):
+            pytest.skip(f"Template file {template_path} not found")
+
+        pkg = Package.open(template_path)
+        # It should create a DocumentPart, not a generic Part
+        assert isinstance(pkg.main_document_part, DocumentPart)
\ No newline at end of file