diff --git a/openstack_releases/cmds/validate.py b/openstack_releases/cmds/validate.py
index 9698716b34..e30a9ed28c 100644
--- a/openstack_releases/cmds/validate.py
+++ b/openstack_releases/cmds/validate.py
@@ -120,6 +120,28 @@ def validate_series_open(deliverable_info,
             expected_branch, previous_deliverable_file, series_name))
 
 
+def validate_series_first(deliverable_info, series_name,
+                          mk_warning, mk_error):
+    "The first release in a series needs to end with '.0'."
+    # When the releases entry is present but empty, it's value may not
+    # be a list, so we default to a list using 'or'.
+    releases = deliverable_info.get('releases') or []
+    if len(releases) != 1:
+        # We only have to check this when the first release is being
+        # applied in the file.
+        return
+    if series_name == '_independent':
+        # These rules don't apply to independent projects.
+        return
+    versionstr = releases[0]['version']
+    patchlevel = versionstr.rpartition('.')[-1]
+    if patchlevel != '0':
+        mk_error(
+            'Initial releases in a series must increment at '
+            'least the minor version. %r' % (versionstr,)
+        )
+
+
 def validate_launchpad(deliverable_info, mk_warning, mk_error):
     "Look for the launchpad project"
     try:
@@ -696,6 +718,12 @@ def main():
                 mk_warning,
                 mk_error,
             )
+        validate_series_first(
+            deliverable_info,
+            series_name,
+            mk_warning,
+            mk_error,
+        )
         validate_branch_prefixes(
             deliverable_info,
             mk_warning,
diff --git a/openstack_releases/tests/test_validate.py b/openstack_releases/tests/test_validate.py
index dab79da7ab..c152172540 100644
--- a/openstack_releases/tests/test_validate.py
+++ b/openstack_releases/tests/test_validate.py
@@ -1506,3 +1506,118 @@ class TestValidateSeriesOpen(base.BaseTestCase):
         print(warnings, errors)
         self.assertEqual(1, len(warnings))
         self.assertEqual(0, len(errors))
+
+
+class TestValidateSeriesFirst(base.BaseTestCase):
+
+    def setUp(self):
+        super(TestValidateSeriesFirst, self).setUp()
+        self.tmpdir = self.useFixture(fixtures.TempDir()).path
+
+    def test_version_ok(self):
+        series_a_dir = self.tmpdir + '/a'
+        series_a_filename = series_a_dir + '/automaton.yaml'
+        os.makedirs(series_a_dir)
+        deliverable_data = textwrap.dedent('''
+        ---
+        releases:
+          - version: 1.5.0
+            projects:
+              - repo: openstack/automaton
+                hash: be2885f544637e6ee6139df7dc7bf937925804dd
+        ''')
+        with open(series_a_filename, 'w') as f:
+            f.write(deliverable_data)
+        warnings = []
+        errors = []
+        deliverable_info = yaml.safe_load(deliverable_data)
+        validate.validate_series_first(
+            deliverable_info,
+            'a',
+            warnings.append,
+            errors.append,
+        )
+        print(warnings, errors)
+        self.assertEqual(0, len(warnings))
+        self.assertEqual(0, len(errors))
+
+    def test_ignore_if_second_release(self):
+        series_a_dir = self.tmpdir + '/a'
+        series_a_filename = series_a_dir + '/automaton.yaml'
+        os.makedirs(series_a_dir)
+        deliverable_data = textwrap.dedent('''
+        ---
+        releases:
+          - version: 1.5.1
+            projects:
+              - repo: openstack/automaton
+                hash: be2885f544637e6ee6139df7dc7bf937925804dd
+          - version: 1.5.2
+            projects:
+              - repo: openstack/automaton
+                hash: be2885f544637e6ee6139df7dc7bf937925804dd
+        ''')
+        with open(series_a_filename, 'w') as f:
+            f.write(deliverable_data)
+        warnings = []
+        errors = []
+        deliverable_info = yaml.safe_load(deliverable_data)
+        validate.validate_series_first(
+            deliverable_info,
+            'a',
+            warnings.append,
+            errors.append,
+        )
+        print(warnings, errors)
+        self.assertEqual(0, len(warnings))
+        self.assertEqual(0, len(errors))
+
+    def test_ignore_if_no_releases(self):
+        series_a_dir = self.tmpdir + '/a'
+        series_a_filename = series_a_dir + '/automaton.yaml'
+        os.makedirs(series_a_dir)
+        deliverable_data = textwrap.dedent('''
+        ---
+        releases:
+        ''')
+        with open(series_a_filename, 'w') as f:
+            f.write(deliverable_data)
+        warnings = []
+        errors = []
+        deliverable_info = yaml.safe_load(deliverable_data)
+        validate.validate_series_first(
+            deliverable_info,
+            'a',
+            warnings.append,
+            errors.append,
+        )
+        print(warnings, errors)
+        self.assertEqual(0, len(warnings))
+        self.assertEqual(0, len(errors))
+
+    def test_version_bad(self):
+        series_a_dir = self.tmpdir + '/a'
+        series_a_filename = series_a_dir + '/automaton.yaml'
+        os.makedirs(series_a_dir)
+        deliverable_data = textwrap.dedent('''
+        ---
+        releases:
+          - version: 1.5.1
+            projects:
+              - repo: openstack/automaton
+                hash: be2885f544637e6ee6139df7dc7bf937925804dd
+        ''')
+        with open(series_a_filename, 'w') as f:
+            f.write(deliverable_data)
+        warnings = []
+        errors = []
+        deliverable_info = yaml.safe_load(deliverable_data)
+        validate.validate_series_first(
+            deliverable_info,
+            'a',
+            warnings.append,
+            errors.append,
+        )
+        print(warnings, errors)
+        self.assertEqual(0, len(warnings))
+        self.assertEqual(1, len(errors))