diff --git a/docs/configuration.rst b/docs/configuration.rst
index 661e506..517e098 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -102,8 +102,15 @@ Errors and warnings
 -------------------
 
 Problems detected by yamllint can be raised either as errors or as warnings.
+The CLI will output them (with different colors when using the ``standard``
+output format).
 
-In both cases, the script will output them (with different colors when using the
-``standard`` output format), but the exit code can be different. More precisely,
-the script will exit will a failure code *only when* there is one or more
-error(s).
+By default the script will exit will a return code ``1`` *only when* there is one or
+more error(s).
+
+However if strict mode is enabled with the ``-s`` (or ``--strict``) option, the
+return code will be:
+
+ * ``0`` if no errors or warnings occur
+ * ``1`` if one or more errors occur
+ * ``2`` if no errors occur, but one or more warnings occur
diff --git a/tests/test_cli.py b/tests/test_cli.py
index da139a8..8a5bab5 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -40,6 +40,10 @@ class CommandLineTestCase(unittest.TestCase):
                     '- 1   \n'
                     '- 2')
 
+        # file with only one warning
+        with open(os.path.join(self.wd, 'warn.yaml'), 'w') as f:
+            f.write('key: value\n')
+
         # .yml file at root
         open(os.path.join(self.wd, 'empty.yml'), 'w').close()
 
@@ -85,7 +89,8 @@ class CommandLineTestCase(unittest.TestCase):
             [os.path.join(self.wd, 'a.yaml'),
              os.path.join(self.wd, 'empty.yml'),
              os.path.join(self.wd, 's/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'),
-             os.path.join(self.wd, 'sub/ok.yaml')],
+             os.path.join(self.wd, 'sub/ok.yaml'),
+             os.path.join(self.wd, 'warn.yaml')],
         )
 
         items = [os.path.join(self.wd, 'sub/ok.yaml'),
@@ -247,6 +252,24 @@ class CommandLineTestCase(unittest.TestCase):
             '(new-line-at-end-of-file)\n') % (file, file))
         self.assertEqual(err, '')
 
+    def test_run_one_warning(self):
+        file = os.path.join(self.wd, 'warn.yaml')
+
+        sys.stdout, sys.stderr = StringIO(), StringIO()
+        with self.assertRaises(SystemExit) as ctx:
+            cli.run(('-f', 'parsable', file))
+
+        self.assertEqual(ctx.exception.code, 0)
+
+    def test_run_warning_in_strict_mode(self):
+        file = os.path.join(self.wd, 'warn.yaml')
+
+        sys.stdout, sys.stderr = StringIO(), StringIO()
+        with self.assertRaises(SystemExit) as ctx:
+            cli.run(('-f', 'parsable', '--strict', file))
+
+        self.assertEqual(ctx.exception.code, 2)
+
     def test_run_one_ok_file(self):
         file = os.path.join(self.wd, 'sub', 'ok.yaml')
 
diff --git a/yamllint/cli.py b/yamllint/cli.py
index 9e3e5f3..1a22f73 100644
--- a/yamllint/cli.py
+++ b/yamllint/cli.py
@@ -22,6 +22,7 @@ import argparse
 
 from yamllint import APP_DESCRIPTION, APP_NAME, APP_VERSION
 from yamllint.config import YamlLintConfig, YamlLintConfigError
+from yamllint.linter import PROBLEM_LEVELS
 from yamllint import linter
 
 
@@ -85,6 +86,10 @@ def run(argv=None):
     parser.add_argument('-f', '--format',
                         choices=('parsable', 'standard'), default='standard',
                         help='format for parsing output')
+    parser.add_argument('-s', '--strict',
+                        action='store_true',
+                        help='return non-zero exit code on warnings '
+                             'as well as errors')
     parser.add_argument('-v', '--version', action='version',
                         version='%s %s' % (APP_NAME, APP_VERSION))
 
@@ -121,7 +126,7 @@ def run(argv=None):
         print(e, file=sys.stderr)
         sys.exit(-1)
 
-    return_code = 0
+    max_level = 0
 
     for file in find_files_recursively(args.files):
         try:
@@ -143,13 +148,19 @@ def run(argv=None):
 
                         print(Format.standard(problem, file))
 
-                    if return_code == 0 and problem.level == 'error':
-                        return_code = 1
+                    max_level = max(max_level, PROBLEM_LEVELS[problem.level])
 
             if not first and args.format != 'parsable':
                 print('')
         except EnvironmentError as e:
             print(e, file=sys.stderr)
-            return_code = -1
+            sys.exit(-1)
+
+    if max_level == PROBLEM_LEVELS['error']:
+        return_code = 1
+    elif max_level == PROBLEM_LEVELS['warning']:
+        return_code = 2 if args.strict else 0
+    else:
+        return_code = 0
 
     sys.exit(return_code)
diff --git a/yamllint/linter.py b/yamllint/linter.py
index b546e8a..1698556 100644
--- a/yamllint/linter.py
+++ b/yamllint/linter.py
@@ -21,6 +21,16 @@ import yaml
 from yamllint import parser
 
 
+PROBLEM_LEVELS = {
+    0: None,
+    1: 'warning',
+    2: 'error',
+    None: 0,
+    'warning': 1,
+    'error': 2,
+}
+
+
 class LintProblem(object):
     """Represents a linting problem found by yamllint."""
     def __init__(self, line, column, desc='<no description>', rule=None):