diff --git a/README.md b/README.md
index 267e96a6..86b27191 100644
--- a/README.md
+++ b/README.md
@@ -114,7 +114,11 @@ Matchers
 ### Booleans
 
 * `false` - Always fail.
+* `? is a boolean` - Assert a value is true or false.
+  * `? is a bool`
 * `? is false` - Assert value is false.
+* `? is not a boolean` - Assert a value is not true or false.
+  * `? is not a bool`
 * `? is true` - Assert a value is true.
 * `true` - Always pass.
 
diff --git a/src/Concise/Matcher/IsABoolean.php b/src/Concise/Matcher/IsABoolean.php
new file mode 100644
index 00000000..7ac4765f
--- /dev/null
+++ b/src/Concise/Matcher/IsABoolean.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Concise\Matcher;
+
+class IsABoolean extends AbstractMatcher
+{
+    public function supportedSyntaxes()
+    {
+        return array(
+            '? is a boolean' => 'Assert a value is true or false.',
+            '? is a bool' => 'Assert a value is true or false.',
+        );
+    }
+
+    public function match($syntax, array $data = array())
+    {
+        return is_bool($data[0]);
+    }
+
+    public function getTags()
+    {
+        return array(Tag::BOOLEANS);
+    }
+}
diff --git a/src/Concise/Matcher/IsNotABoolean.php b/src/Concise/Matcher/IsNotABoolean.php
new file mode 100644
index 00000000..b8fe9892
--- /dev/null
+++ b/src/Concise/Matcher/IsNotABoolean.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Concise\Matcher;
+
+class IsNotABoolean extends IsABoolean
+{
+    public function supportedSyntaxes()
+    {
+        return array(
+            '? is not a boolean' => 'Assert a value is not true or false.',
+            '? is not a bool' => 'Assert a value is not true or false.',
+        );
+    }
+
+    public function match($syntax, array $data = array())
+    {
+        return !parent::match(null, $data);
+    }
+
+    public function getTags()
+    {
+        return array(Tag::BOOLEANS);
+    }
+}
diff --git a/tests/Concise/Matcher/IsABooleanTest.php b/tests/Concise/Matcher/IsABooleanTest.php
new file mode 100644
index 00000000..3e76f65d
--- /dev/null
+++ b/tests/Concise/Matcher/IsABooleanTest.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Concise\Matcher;
+
+class IsABooleanTest extends AbstractMatcherTestCase
+{
+    public function setUp()
+    {
+        parent::setUp();
+        $this->matcher = new IsABoolean();
+    }
+
+    public function testTrueIsABoolean()
+    {
+        $this->assert(true, is_a_boolean);
+    }
+
+    public function testAStringIsNotABoolean()
+    {
+        $this->assertFailure("true", is_a_boolean);
+    }
+
+    public function testFalseIsABoolean()
+    {
+        $this->assert(false, is_a_boolean);
+    }
+
+    public function testAlternativeShorterSyntax()
+    {
+        $this->assert(true, is_a_bool);
+    }
+}
diff --git a/tests/Concise/Matcher/IsNotABooleanTest.php b/tests/Concise/Matcher/IsNotABooleanTest.php
new file mode 100644
index 00000000..016e3fd1
--- /dev/null
+++ b/tests/Concise/Matcher/IsNotABooleanTest.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Concise\Matcher;
+
+class IsNotABooleanTest extends AbstractMatcherTestCase
+{
+    public function setUp()
+    {
+        parent::setUp();
+        $this->matcher = new IsNotABoolean();
+    }
+
+    public function testTrueIsABoolean()
+    {
+        $this->assertFailure(true, is_not_a_boolean);
+    }
+
+    public function testAStringIsNotABoolean()
+    {
+        $this->assert("true", is_not_a_boolean);
+    }
+
+    public function testFalseIsABoolean()
+    {
+        $this->assertFailure(false, is_not_a_boolean);
+    }
+
+    public function testAlternativeShorterSyntax()
+    {
+        $this->assertFailure(true, is_not_a_bool);
+    }
+}
diff --git a/wiki b/wiki
index 2a497658..a241f94a 160000
--- a/wiki
+++ b/wiki
@@ -1 +1 @@
-Subproject commit 2a497658cf861d0c13de28ad48d7159e59b17f07
+Subproject commit a241f94a6112d27d6daa6c168b807a87d6dd3403