diff --git a/src/AbstractMultiton.php b/src/AbstractMultiton.php
index fff55b1..3c6c4c9 100644
--- a/src/AbstractMultiton.php
+++ b/src/AbstractMultiton.php
@@ -19,22 +19,6 @@
  */
 abstract class AbstractMultiton implements MultitonInterface
 {
-    /**
-     * Returns an array of all members in this multiton.
-     *
-     * @return array<string,MultitonInterface> All members.
-     */
-    final public static function members()
-    {
-        $class = get_called_class();
-        if (!array_key_exists($class, self::$members)) {
-            self::$members[$class] = array();
-            static::initializeMembers();
-        }
-
-        return self::$members[$class];
-    }
-
     /**
      * Returns a single member by string key.
      *
@@ -147,41 +131,40 @@ function (MultitonInterface $member) use (
     }
 
     /**
-     * Returns a set of members by comparison with the result of an accessor
-     * method.
+     * Returns a single member by comparison with the result of an accessor
+     * method. Additionally returns null if the supplied value is null.
      *
      * @param string       $property        The name of the property (accessor method) to match.
-     * @param mixed        $value           The value to match.
+     * @param mixed        $value           The value to match, or null.
      * @param boolean|null $isCaseSensitive True if the search should be case sensitive.
      *
-     * @return array<string,MultitonInterface> All members for which $member->{$property}() === $value.
+     * @return MultitonInterface|null                      The first member for which $member->{$property}() === $value, or null if the supplied value is null.
+     * @throws Exception\UndefinedMemberExceptionInterface If no associated member is found.
      */
-    final public static function membersBy(
+    final public static function memberOrNullBy(
         $property,
         $value,
         $isCaseSensitive = null
     ) {
-        if (null === $isCaseSensitive) {
-            $isCaseSensitive = true;
-        }
-        if (!$isCaseSensitive && is_scalar($value)) {
-            $value = strtoupper(strval($value));
-        }
+        $member = static::memberByWithDefault(
+            $property,
+            $value,
+            null,
+            $isCaseSensitive
+        );
+        if (null === $member) {
+            if (null === $value) {
+                return null;
+            }
 
-        return static::membersByPredicate(
-            function (MultitonInterface $member) use (
+            throw static::createUndefinedMemberException(
+                get_called_class(),
                 $property,
-                $value,
-                $isCaseSensitive
-            ) {
-                $memberValue = $member->{$property}();
-                if (!$isCaseSensitive && is_scalar($memberValue)) {
-                    $memberValue = strtoupper(strval($memberValue));
-                }
+                $value
+            );
+        }
 
-                return $memberValue === $value;
-            }
-        );
+        return $member;
     }
 
     /**
@@ -228,6 +211,60 @@ final public static function memberByPredicateWithDefault(
         return $default;
     }
 
+    /**
+     * Returns an array of all members in this multiton.
+     *
+     * @return array<string,MultitonInterface> All members.
+     */
+    final public static function members()
+    {
+        $class = get_called_class();
+        if (!array_key_exists($class, self::$members)) {
+            self::$members[$class] = array();
+            static::initializeMembers();
+        }
+
+        return self::$members[$class];
+    }
+
+    /**
+     * Returns a set of members by comparison with the result of an accessor
+     * method.
+     *
+     * @param string       $property        The name of the property (accessor method) to match.
+     * @param mixed        $value           The value to match.
+     * @param boolean|null $isCaseSensitive True if the search should be case sensitive.
+     *
+     * @return array<string,MultitonInterface> All members for which $member->{$property}() === $value.
+     */
+    final public static function membersBy(
+        $property,
+        $value,
+        $isCaseSensitive = null
+    ) {
+        if (null === $isCaseSensitive) {
+            $isCaseSensitive = true;
+        }
+        if (!$isCaseSensitive && is_scalar($value)) {
+            $value = strtoupper(strval($value));
+        }
+
+        return static::membersByPredicate(
+            function (MultitonInterface $member) use (
+                $property,
+                $value,
+                $isCaseSensitive
+            ) {
+                $memberValue = $member->{$property}();
+                if (!$isCaseSensitive && is_scalar($memberValue)) {
+                    $memberValue = strtoupper(strval($memberValue));
+                }
+
+                return $memberValue === $value;
+            }
+        );
+    }
+
     /**
      * Returns a set of members by predicate callback.
      *
diff --git a/src/AbstractValueMultiton.php b/src/AbstractValueMultiton.php
index ead96ed..7404456 100644
--- a/src/AbstractValueMultiton.php
+++ b/src/AbstractValueMultiton.php
@@ -31,19 +31,6 @@ final public static function memberByValue($value, $isCaseSensitive = null)
         return static::memberBy('value', $value, $isCaseSensitive);
     }
 
-    /**
-     * Returns a set of members matching the supplied value.
-     *
-     * @param scalar       $value           The value associated with the members.
-     * @param boolean|null $isCaseSensitive True if the search should be case sensitive.
-     *
-     * @return array<string,ValueMultitonInterface> All members with the supplied value.
-     */
-    final public static function membersByValue($value, $isCaseSensitive = null)
-    {
-        return static::membersBy('value', $value, $isCaseSensitive);
-    }
-
     /**
      * Returns a single member by value. Additionally returns a default if no
      * associated member is found.
@@ -67,6 +54,35 @@ final public static function memberByValueWithDefault(
         );
     }
 
+    /**
+     * Returns a single member by value.
+     *
+     * @param scalar|null  $value           The value associated with the member, or null.
+     * @param boolean|null $isCaseSensitive True if the search should be case sensitive.
+     *
+     * @return ValueMultitonInterface|null        The first member with the supplied value, or null if the supplied value is null.
+     * @throws Exception\UndefinedMemberException If no associated member is found.
+     */
+    final public static function memberOrNullByValue(
+        $value,
+        $isCaseSensitive = null
+    ) {
+        return static::memberOrNullBy('value', $value, $isCaseSensitive);
+    }
+
+    /**
+     * Returns a set of members matching the supplied value.
+     *
+     * @param scalar       $value           The value associated with the members.
+     * @param boolean|null $isCaseSensitive True if the search should be case sensitive.
+     *
+     * @return array<string,ValueMultitonInterface> All members with the supplied value.
+     */
+    final public static function membersByValue($value, $isCaseSensitive = null)
+    {
+        return static::membersBy('value', $value, $isCaseSensitive);
+    }
+
     /**
      * Returns the value of this member.
      *
diff --git a/test/suite/AbstractEnumerationTest.php b/test/suite/AbstractEnumerationTest.php
index 20d3389..b71f116 100644
--- a/test/suite/AbstractEnumerationTest.php
+++ b/test/suite/AbstractEnumerationTest.php
@@ -30,15 +30,6 @@ protected function setUp()
 
     // Multiton tests ==========================================================
 
-    public function testMembers()
-    {
-        $this->assertSame(array(
-            'BAZ' => ValidEnumeration::BAZ(),
-            'FOO' => ValidEnumeration::FOO(),
-            'BAR' => ValidEnumeration::BAR(),
-        ), ValidEnumeration::members());
-    }
-
     public function testMemberByKey()
     {
         $foo = ValidEnumeration::memberByKey('FOO');
@@ -101,13 +92,18 @@ public function testMemberByWithDefault()
         $this->assertNull(ValidEnumeration::memberByWithDefault('key', 'qux'));
     }
 
-    public function testMembersBy()
+    public function testMemberOrNullBy()
     {
-        $foo = ValidEnumeration::membersBy('value', 'oof');
-        $bar = ValidEnumeration::membersBy('value', 'RAB', false);
+        $this->assertSame(ValidEnumeration::FOO(), ValidEnumeration::memberOrNullBy('key', 'FOO'));
+        $this->assertSame(ValidEnumeration::BAR(), ValidEnumeration::memberOrNullBy('key', 'BAR'));
+        $this->assertSame(ValidEnumeration::FOO(), ValidEnumeration::memberOrNullBy('key', 'Foo', false));
+        $this->assertNull(ValidEnumeration::memberOrNullBy('key', null));
+    }
 
-        $this->assertSame(array('FOO' => ValidEnumeration::FOO()), $foo);
-        $this->assertSame(array('BAR' => ValidEnumeration::BAR()), $bar);
+    public function testMemberOrNullByFailureUndefined()
+    {
+        $this->setExpectedException('Eloquent\Enumeration\Exception\UndefinedMemberException');
+        ValidEnumeration::memberOrNullBy('key', 'DOOM');
     }
 
     public function testMemberByPredicate()
@@ -170,6 +166,24 @@ function (ValidEnumeration $member) {
         $this->assertNull($defaultNull);
     }
 
+    public function testMembers()
+    {
+        $this->assertSame(array(
+            'BAZ' => ValidEnumeration::BAZ(),
+            'FOO' => ValidEnumeration::FOO(),
+            'BAR' => ValidEnumeration::BAR(),
+        ), ValidEnumeration::members());
+    }
+
+    public function testMembersBy()
+    {
+        $foo = ValidEnumeration::membersBy('value', 'oof');
+        $bar = ValidEnumeration::membersBy('value', 'RAB', false);
+
+        $this->assertSame(array('FOO' => ValidEnumeration::FOO()), $foo);
+        $this->assertSame(array('BAR' => ValidEnumeration::BAR()), $bar);
+    }
+
     public function testMembersByPredicate()
     {
         $notBaz = ValidEnumeration::membersByPredicate(
@@ -280,6 +294,20 @@ public function testMemberByValueWithDefault()
         $this->assertNull(ValidEnumeration::memberByValueWithDefault('qux'));
     }
 
+    public function testMemberOrNullByValue()
+    {
+        $this->assertSame(ValidEnumeration::FOO(), ValidEnumeration::memberOrNullByValue('oof'));
+        $this->assertSame(ValidEnumeration::BAR(), ValidEnumeration::memberOrNullByValue('rab'));
+        $this->assertSame(ValidEnumeration::FOO(), ValidEnumeration::memberOrNullByValue('Oof', false));
+        $this->assertNull(ValidEnumeration::memberOrNullByValue(null));
+    }
+
+    public function testMemberOrNullByValueFailureUndefined()
+    {
+        $this->setExpectedException('Eloquent\Enumeration\Exception\UndefinedMemberException');
+        ValidEnumeration::memberOrNullByValue('mood');
+    }
+
     public function testMembersByValue()
     {
         $this->assertSame(array('FOO' => ValidEnumeration::FOO()), ValidEnumeration::membersByValue('oof'));
diff --git a/test/suite/AbstractMultitonTest.php b/test/suite/AbstractMultitonTest.php
index a3a9bf8..7461f3a 100644
--- a/test/suite/AbstractMultitonTest.php
+++ b/test/suite/AbstractMultitonTest.php
@@ -32,18 +32,6 @@ protected function setUp()
 
     // Multiton tests ==========================================================
 
-    public function testMembers()
-    {
-        $this->assertSame(
-            array(
-                'FOO' => ValidMultiton::FOO(),
-                'BAR' => ValidMultiton::BAR(),
-                'BAZ' => ValidMultiton::BAZ(),
-            ),
-            ValidMultiton::members()
-        );
-    }
-
     public function testMemberByKey()
     {
         $this->assertSame(array(), ValidMultiton::calls());
@@ -118,22 +106,18 @@ public function testMemberByWithDefault()
         $this->assertNull(ValidMultiton::memberByWithDefault('key', 'qux'));
     }
 
-    public function testMembersBy()
+    public function testMemberOrNullBy()
     {
-        $this->assertSame(array(), ValidMultiton::calls());
-
-        $foo = ValidMultiton::membersBy('value', 'oof');
-        $bar = ValidMultiton::membersBy('value', 'RAB', false);
-
-        $this->assertSame(array('FOO' => ValidMultiton::FOO()), $foo);
-        $this->assertSame(array('BAR' => ValidMultiton::BAR()), $bar);
+        $this->assertSame(ValidMultiton::FOO(), ValidMultiton::memberOrNullBy('key', 'FOO'));
+        $this->assertSame(ValidMultiton::BAR(), ValidMultiton::memberOrNullBy('key', 'BAR'));
+        $this->assertSame(ValidMultiton::FOO(), ValidMultiton::memberOrNullBy('key', 'Foo', false));
+        $this->assertNull(ValidMultiton::memberOrNullBy('key', null));
+    }
 
-        $this->assertSame(array(
-            array(
-                'Eloquent\Enumeration\Test\Fixture\ValidMultiton::initializeMembers',
-                array(),
-            ),
-        ), ValidMultiton::calls());
+    public function testMemberOrNullByFailureUndefined()
+    {
+        $this->setExpectedException('Eloquent\Enumeration\Exception\UndefinedMemberException');
+        ValidMultiton::memberOrNullBy('key', 'DOOM');
     }
 
     public function testMemberByPredicate()
@@ -205,6 +189,36 @@ function (ValidMultiton $member) {
         $this->assertNull($defaultNull);
     }
 
+    public function testMembers()
+    {
+        $this->assertSame(
+            array(
+                'FOO' => ValidMultiton::FOO(),
+                'BAR' => ValidMultiton::BAR(),
+                'BAZ' => ValidMultiton::BAZ(),
+            ),
+            ValidMultiton::members()
+        );
+    }
+
+    public function testMembersBy()
+    {
+        $this->assertSame(array(), ValidMultiton::calls());
+
+        $foo = ValidMultiton::membersBy('value', 'oof');
+        $bar = ValidMultiton::membersBy('value', 'RAB', false);
+
+        $this->assertSame(array('FOO' => ValidMultiton::FOO()), $foo);
+        $this->assertSame(array('BAR' => ValidMultiton::BAR()), $bar);
+
+        $this->assertSame(array(
+            array(
+                'Eloquent\Enumeration\Test\Fixture\ValidMultiton::initializeMembers',
+                array(),
+            ),
+        ), ValidMultiton::calls());
+    }
+
     public function testMembersByPredicate()
     {
         $this->assertSame(array(), ValidMultiton::calls());
diff --git a/test/suite/AbstractValueMultitonTest.php b/test/suite/AbstractValueMultitonTest.php
index 8da4798..10645b2 100644
--- a/test/suite/AbstractValueMultitonTest.php
+++ b/test/suite/AbstractValueMultitonTest.php
@@ -32,15 +32,6 @@ protected function setUp()
 
     // Multiton tests ==========================================================
 
-    public function testMembers()
-    {
-        $this->assertSame(array(
-            'FOO' => ValidValueMultiton::FOO(),
-            'BAR' => ValidValueMultiton::BAR(),
-            'BAZ' => ValidValueMultiton::BAZ(),
-        ), ValidValueMultiton::members());
-    }
-
     public function testMemberByKey()
     {
         $this->assertSame(array(), ValidValueMultiton::calls());
@@ -115,22 +106,18 @@ public function testMemberByWithDefault()
         $this->assertNull(ValidValueMultiton::memberByWithDefault('key', 'qux'));
     }
 
-    public function testMembersBy()
+    public function testMemberOrNullBy()
     {
-        $this->assertSame(array(), ValidValueMultiton::calls());
-
-        $foo = ValidValueMultiton::membersBy('value', 'oof');
-        $bar = ValidValueMultiton::membersBy('value', 'RAB', false);
-
-        $this->assertSame(array('FOO' => ValidValueMultiton::FOO()), $foo);
-        $this->assertSame(array('BAR' => ValidValueMultiton::BAR()), $bar);
+        $this->assertSame(ValidValueMultiton::FOO(), ValidValueMultiton::memberOrNullBy('key', 'FOO'));
+        $this->assertSame(ValidValueMultiton::BAR(), ValidValueMultiton::memberOrNullBy('key', 'BAR'));
+        $this->assertSame(ValidValueMultiton::FOO(), ValidValueMultiton::memberOrNullBy('key', 'Foo', false));
+        $this->assertNull(ValidValueMultiton::memberOrNullBy('key', null));
+    }
 
-        $this->assertSame(array(
-            array(
-                'Eloquent\Enumeration\Test\Fixture\ValidValueMultiton::initializeMembers',
-                array(),
-            ),
-        ), ValidValueMultiton::calls());
+    public function testMemberOrNullByFailureUndefined()
+    {
+        $this->setExpectedException('Eloquent\Enumeration\Exception\UndefinedMemberException');
+        ValidValueMultiton::memberOrNullBy('key', 'DOOM');
     }
 
     public function testMemberByPredicate()
@@ -202,6 +189,33 @@ function (ValidValueMultiton $member) {
         $this->assertNull($defaultNull);
     }
 
+    public function testMembers()
+    {
+        $this->assertSame(array(
+            'FOO' => ValidValueMultiton::FOO(),
+            'BAR' => ValidValueMultiton::BAR(),
+            'BAZ' => ValidValueMultiton::BAZ(),
+        ), ValidValueMultiton::members());
+    }
+
+    public function testMembersBy()
+    {
+        $this->assertSame(array(), ValidValueMultiton::calls());
+
+        $foo = ValidValueMultiton::membersBy('value', 'oof');
+        $bar = ValidValueMultiton::membersBy('value', 'RAB', false);
+
+        $this->assertSame(array('FOO' => ValidValueMultiton::FOO()), $foo);
+        $this->assertSame(array('BAR' => ValidValueMultiton::BAR()), $bar);
+
+        $this->assertSame(array(
+            array(
+                'Eloquent\Enumeration\Test\Fixture\ValidValueMultiton::initializeMembers',
+                array(),
+            ),
+        ), ValidValueMultiton::calls());
+    }
+
     public function testMembersByPredicate()
     {
         $this->assertSame(array(), ValidValueMultiton::calls());
@@ -309,18 +323,9 @@ public function testMemberByValueFailureUndefined()
 
     public function testMemberByValueWithDefault()
     {
-        $this->assertSame(
-            ValidValueMultiton::FOO(),
-            ValidValueMultiton::memberByValueWithDefault('oof')
-        );
-        $this->assertSame(
-            ValidValueMultiton::BAR(),
-            ValidValueMultiton::memberByValueWithDefault('rab')
-        );
-        $this->assertSame(
-            ValidValueMultiton::FOO(),
-            ValidValueMultiton::memberByValueWithDefault('Oof', null, false)
-        );
+        $this->assertSame(ValidValueMultiton::FOO(), ValidValueMultiton::memberByValueWithDefault('oof'));
+        $this->assertSame(ValidValueMultiton::BAR(), ValidValueMultiton::memberByValueWithDefault('rab'));
+        $this->assertSame(ValidValueMultiton::FOO(), ValidValueMultiton::memberByValueWithDefault('Oof', null, false));
         $this->assertSame(
             ValidValueMultiton::FOO(),
             ValidValueMultiton::memberByValueWithDefault('qux', ValidValueMultiton::FOO())
@@ -328,6 +333,20 @@ public function testMemberByValueWithDefault()
         $this->assertNull(ValidValueMultiton::memberByValueWithDefault('qux'));
     }
 
+    public function testMemberOrNullByValue()
+    {
+        $this->assertSame(ValidValueMultiton::FOO(), ValidValueMultiton::memberOrNullByValue('oof'));
+        $this->assertSame(ValidValueMultiton::BAR(), ValidValueMultiton::memberOrNullByValue('rab'));
+        $this->assertSame(ValidValueMultiton::FOO(), ValidValueMultiton::memberOrNullByValue('Oof', false));
+        $this->assertNull(ValidValueMultiton::memberOrNullByValue(null));
+    }
+
+    public function testMemberOrNullByValueFailureUndefined()
+    {
+        $this->setExpectedException('Eloquent\Enumeration\Exception\UndefinedMemberException');
+        ValidValueMultiton::memberOrNullByValue('mood');
+    }
+
     public function testMembersByValue()
     {
         $this->assertSame(array('FOO' => ValidValueMultiton::FOO()), ValidValueMultiton::membersByValue('oof'));