diff --git a/sdks/python/apache_beam/transforms/window.py b/sdks/python/apache_beam/transforms/window.py
index 1a0c3007b4f1..e405f8b7db23 100644
--- a/sdks/python/apache_beam/transforms/window.py
+++ b/sdks/python/apache_beam/transforms/window.py
@@ -474,6 +474,8 @@ def __init__(
   ):
     if size <= 0:
       raise ValueError('The size parameter must be strictly positive.')
+    if period <= 0:
+      raise ValueError('The period parameter must be strictly positive.')
     self.size = Duration.of(size)
     self.period = Duration.of(period)
     self.offset = Timestamp.of(offset) % period
diff --git a/sdks/python/apache_beam/transforms/window_test.py b/sdks/python/apache_beam/transforms/window_test.py
index 9c3ee11e4a2e..d13a9a78d765 100644
--- a/sdks/python/apache_beam/transforms/window_test.py
+++ b/sdks/python/apache_beam/transforms/window_test.py
@@ -137,6 +137,14 @@ def test_sliding_windows_assignment_fraction_large_offset(self):
     self.assertEqual([IntervalWindow(4.0, 7.5), IntervalWindow(1.5, 5.0)],
                      windowfn.assign(context('v', 4.5)))
 
+  def test_sliding_windows_non_positive_period(self):
+    # Control: the sibling window function already rejects a non-positive size.
+    with self.assertRaises(ValueError):
+      FixedWindows(size=0)
+    for period in (0, -5):
+      with self.assertRaisesRegex(ValueError, 'period'):
+        SlidingWindows(size=10, period=period)
+
   def test_sessions_merging(self):
     windowfn = Sessions(10)