diff --git a/tests/data/storyformat.st.txt b/tests/data/storyformat.st.txt
new file mode 100644
index 0000000..5483e37
--- /dev/null
+++ b/tests/data/storyformat.st.txt
@@ -0,0 +1,43 @@
+movie: Good Format (2000)
+=========================
+
+:: Title
+Good Format
+
+:: Date
+2000-01-01
+
+:: Description
+A story with a recognized story format.
+
+:: Story Format
+film
+
+
+movie: Bad Format (2001)
+========================
+
+:: Title
+Bad Format
+
+:: Date
+2001-01-01
+
+:: Description
+A story with an unrecognized story format.
+
+:: Story Format
+graphic novel
+
+
+movie: No Format (2002)
+=======================
+
+:: Title
+No Format
+
+:: Date
+2002-01-01
+
+:: Description
+A story that omits the story format field entirely.
diff --git a/tests/test_totolo.py b/tests/test_totolo.py
index 34b4414..ddc0b0f 100644
--- a/tests/test_totolo.py
+++ b/tests/test_totolo.py
@@ -406,6 +406,16 @@ def test_multiple_entries(self):
         warnings = list(ontology._impl.validate_entries())
         assert any("Multiple TOStory with name" in x for x in warnings)
 
+    def test_storyformat_warning(self):
+        ontology = totolo.files("tests/data/storyformat.st.txt")
+        warnings = list(ontology._impl.validate_storyformat())
+        assert any("Bad Format" in x and "graphic novel" in x for x in warnings)
+        assert not any("Good Format" in x for x in warnings)
+        assert not any("No Format" in x for x in warnings)
+        # surfaces through the public validate() entry point as well
+        assert any(
+            "Unrecognized 'story format'" in x for x in ontology.validate()
+        )
     def test_component_warning(self):
         ontology = totolo.files("tests/data/dangling-component.st.txt")
         warnings = list(ontology._impl.validate_components())
diff --git a/totolo/__init__.py b/totolo/__init__.py
index 8205d33..13dd175 100644
--- a/totolo/__init__.py
+++ b/totolo/__init__.py
@@ -5,7 +5,7 @@
 
 
 remote = TORemote()
-__version__ = "2.1.4"
+__version__ = "2.2.0"
 __ALL__ = [
     empty,
     files,
diff --git a/totolo/impl/to_base.py b/totolo/impl/to_base.py
index 28c3417..b0cb53f 100644
--- a/totolo/impl/to_base.py
+++ b/totolo/impl/to_base.py
@@ -10,6 +10,18 @@
 from .to_containers import TODict
 
 
+#: Permitted values for the optional "Story Format" field on a story. This is a
+#: high-level, objective classification of the medium (not genre). The field may
+#: be omitted entirely; if present it must be one of these values.
+STORY_FORMATS = frozenset({
+    "film",
+    "tv",
+    "stage",
+    "prose",
+    "game",
+})
+
+
 class TOBase(TOObject):
     story = a(TODict)
     theme = a(TODict)
@@ -159,6 +171,7 @@ def organize_collections(self):
     def validate(self):
         yield from self._impl.validate_entries()
         yield from self._impl.validate_storythemes()
+        yield from self._impl.validate_storyformat()
         yield from self._impl.validate_components()
         yield from self._impl.validate_cycles()
 
@@ -300,6 +313,14 @@ def validate_storythemes(self):
                         yield (f"{story.name}: Undefined '{weight} theme' with "
                                f"name '{kwfield.keyword}'")
 
+    def validate_storyformat(self):
+        """Detect stories whose 'Story Format' is set to an unrecognized value."""
+        for story in self.o.stories():
+            value = str(story.get("Story Format")).strip()
+            if value and value not in STORY_FORMATS:
+                allowed = ", ".join(sorted(STORY_FORMATS))
+                yield (f"{story.name}: Unrecognized 'story format' "
+                       f"'{value}' (expected one of: {allowed})")
     def validate_components(self):
         """Detect component stories of collections that reference undefined stories."""
         for story in self.o.stories():
diff --git a/totolo/story.py b/totolo/story.py
index 1e1d608..3006cbc 100644
--- a/totolo/story.py
+++ b/totolo/story.py
@@ -21,6 +21,7 @@ class TOStory(TOEntry):
     Collections = sa("list")
     Component_Stories = sa("list")
     Related_Stories = sa("list")
+    Story_Format = sa("text")
     Choice_Themes = sa("kwlist")
     Major_Themes = sa("kwlist")
     Minor_Themes = sa("kwlist")