diff --git a/debug b/debug
new file mode 100644
index 0000000..0e5d74d
--- /dev/null
+++ b/debug
@@ -0,0 +1 @@
+emmental
diff --git a/lib/test_version.py b/lib/test_version.py
new file mode 100644
index 0000000..8cd4571
--- /dev/null
+++ b/lib/test_version.py
@@ -0,0 +1,13 @@
+# Copyright 2021 (c) Anna Schumaker.
+from . import version
+import unittest
+
+class TestVersion(unittest.TestCase):
+    def test_version(self):
+        self.assertEqual(version.MAJOR, 2)
+        self.assertEqual(version.MINOR, 0)
+
+        self.assertTrue(version.DEBUG)
+        self.assertTrue(version.TESTING)
+
+        self.assertEqual(version.string(), "Emmental 2.0-debug")
diff --git a/lib/version.py b/lib/version.py
new file mode 100644
index 0000000..1b9ebf6
--- /dev/null
+++ b/lib/version.py
@@ -0,0 +1,16 @@
+# Copyright 2021 (c) Anna Schumaker.
+import os
+
+MAJOR = 2
+MINOR = 0
+
+DEBUG = False
+with open("debug") as f:
+    if f.read().strip() == "emmental":
+        DEBUG = True
+
+TESTING = os.environ.get("EMMENTAL_TESTING") != None
+
+
+def string():
+    return f"Emmental {MAJOR}.{MINOR}{'-debug' if DEBUG else ''}"