diff --git a/README.md b/README.md
index b61edb8..18e6137 100644
--- a/README.md
+++ b/README.md
@@ -206,6 +206,18 @@ Aliases: `cast`, `castTo`
 
 Perform a map operation on the value for this option.  Takes function that accepts a string $value and return mixed (you can map to whatever you wish).
 
+### `reduce (Closure $reducer [, mixed $seed])`
+
+Aliases: `list`, `each`, `every`
+
+Execute an accumulator/reducer function on every instance of the option in the command. Takes an accumulator function, and returns mixed (you can return any value). If you also supply a map for the option the map will execute on every value before it is passed to the accumulator function. If `$seed` value is supplied, this will be used as the default value.
+
+Signature: `function(mixed $accumulated, mixed $value) : mixed`
+
+ - `$accumulated`: null|Option::default|mixed (the last value returned from the function, the option default value, or null.)
+ - `$value`: mixed (the value that comes after the option. if map is supplied, the value returned from the map function.)
+ - `return`: mixed (anything you want. The last value returned becomes the value of the Option after parsing.)
+
 ### `referToAs (string $name)`
 
 Aliases: `title`, `referredToAs`
diff --git a/composer.json b/composer.json
index 6c83bd7..dc3f0df 100644
--- a/composer.json
+++ b/composer.json
@@ -18,5 +18,7 @@
     "version": "0.3.0",
     "autoload": {
         "psr-0": {"Commando": "src/"}
+    },
+    "require-dev": {
     }
 }
diff --git a/src/Commando/Command.php b/src/Commando/Command.php
index 26b494e..9121b03 100755
--- a/src/Commando/Command.php
+++ b/src/Commando/Command.php
@@ -122,6 +122,11 @@ class Command implements \ArrayAccess, \Iterator
         'cast' => 'map',
         'castWith' => 'map',
 
+        'reduce' => 'reduce',
+        'each' => 'reduce',
+        'every' => 'reduce',
+        'list' => 'reduce',
+
         'increment' => 'increment',
         'repeatable' => 'increment',
         'repeats' => 'increment',
@@ -340,6 +345,21 @@ private function _map(Option $option, \Closure $callback)
         return $option->setMap($callback);
     }
 
+    /**
+     * @param Option $option
+     * @param \Closure $callback
+     * @return Option
+     */
+    private function _reduce(Option $option, \Closure $callback, $seed = null)
+    {
+        if (isset($seed))
+        {
+            $option->setDefault($seed);
+        }
+        
+        return $option->setReducer($callback);
+    }
+
     /**
      * @param Option $option
      * @param integer $max
@@ -461,6 +481,13 @@ public function parse()
                     }
 
                     $option = $this->getOption($name);
+                    if ($option->hasReducer()) {
+                        if (!isset($keyvals[$name])) {
+                            $acc = $option->getDefault();
+                        } else {
+                            $acc = $keyvals[$name];
+                        }
+                    }
                     if ($option->isBoolean()) {
                         $keyvals[$name] = !$option->getDefault();// inverse of the default, as expected
                     } elseif ($option->isIncrement()) {
@@ -475,14 +502,17 @@ public function parse()
                         list($val, $type) = $this->_parseOption($token);
                         if ($type !== self::OPTION_TYPE_ARGUMENT)
                             throw new \Exception(sprintf('Unable to parse option %s: Expected an argument', $token));
-                        $keyvals[$name] = $val;
+                        if (!$option->hasReducer()) {
+                            $keyvals[$name] = $val;
+                        } else {
+                            $keyvals[$name] = $option->reduce($acc, $option->map($val));
+                        }
                     }
                 }
             }
 
             // Set values (validates and performs map when applicable)
             foreach ($keyvals as $key => $value) {
-
                 $this->getOption($key)->setValue($value);
             }
 
diff --git a/src/Commando/Option.php b/src/Commando/Option.php
index aad7def..5dc5e15 100755
--- a/src/Commando/Option.php
+++ b/src/Commando/Option.php
@@ -34,6 +34,7 @@
  * @method Option defaultsTo (mixed $defaultValue)
  * @method Option file ()
  * @method Option expectsFile ()
+ * @method Option reduce (\Closure $reducer)
  *
  */
 
@@ -51,6 +52,7 @@ class Option
         $type = 0, /* int see constants */
         $rule, /* closure */
         $map, /* closure */
+        $reducer, /* closure */
         $increment = false, /* bool */
         $max_value = 0, /* int max value for increment */
         $default, /* mixed default value for this option when no value is specified */
@@ -132,6 +134,15 @@ public function setIncrement($max = 0)
         return $this;
     }
 
+    /**
+     * @param Callable $reducer
+     * @return Option
+     */
+    public function setReducer(Callable $reducer) {
+        $this->reducer = $reducer;
+        return $this;
+    }
+
     /**
      * Require that the argument is a file.  This will
      * make sure the argument is a valid file, will expand
@@ -243,6 +254,19 @@ public function map($value)
         return call_user_func($this->map, $value);
     }
 
+    /**
+     * @param mixed $value
+     * @return Option
+     */
+    public function reduce($accumulator, $value)
+    {
+        if (!is_callable($this->reducer)) {
+            return $value;
+        }
+
+        return call_user_func($this->reducer, $accumulator, $value);
+    }
+
 
     /**
      * @param mixed $value
@@ -388,6 +412,14 @@ public function hasNeeds($optionsList)
 
     }
 
+    /**
+     * @return boolean True if reducer is set
+     */
+    public function hasReducer()
+    {
+        return is_callable($this->reducer);
+    }
+
     /**
      * @param mixed $value for this option (set on the command line)
      * @throws \Exception
@@ -418,7 +450,11 @@ public function setValue($value)
                 $value = $file_path;
             }
         }
-        $this->value = $this->map($value);
+        if ($this->hasReducer()) {
+            $this->value = $value;
+        } else {
+            $this->value = $this->map($value);
+        }
     }
 
     /**
diff --git a/tests/Commando/CommandTest.php b/tests/Commando/CommandTest.php
index aa137c8..635232d 100755
--- a/tests/Commando/CommandTest.php
+++ b/tests/Commando/CommandTest.php
@@ -144,6 +144,21 @@ public function testBooleanOption()
         $this->assertTrue($cmd['b']);
     }
 
+    public function testReduceOption() {
+        $tokens = array('filename', '--exclude', 'name1', '--exclude', 'name2');
+        $cmd = new Command($tokens);
+        $cmd
+            ->option('exclude')
+            ->reduce(function ($acc, $next) {
+                array_push($acc, $next);
+                return $acc;
+            })
+            ->default([]);
+
+        $this->assertEquals(2, count($cmd['exclude']));
+        $this->assertEquals(array('name1', 'name2'), $cmd['exclude']);
+    }
+
     public function testIncrementOption()
     {
         $tokens = array('filename', '-vvvv');
diff --git a/tests/Commando/OptionTest.php b/tests/Commando/OptionTest.php
index 9694d6b..9f41582 100644
--- a/tests/Commando/OptionTest.php
+++ b/tests/Commando/OptionTest.php
@@ -154,6 +154,36 @@ public function testSetRequired()
         $this->assertTrue(in_array('foo', $option->getNeeds()));
     }
 
+    /**
+     * Test that the reducer gets set
+     */
+    public function testSetReducer()
+    {
+        $option = new Option('f');
+
+        $this->assertTrue(!$option->hasReducer());
+
+        $option->setReducer(function() {});
+        
+        $this->assertTrue($option->hasReducer());
+    }
+
+    /**
+     * Test that reducer is called
+     */
+    public function testReduce()
+    {
+        $option = new Option('f');
+        $isCalled = false;
+        $option->setReducer(function () use (&$isCalled) {
+            $isCalled = true;
+            return ($isCalled);
+        });
+
+        $this->assertTrue($option->reduce(null, null));
+        $this->assertTrue($isCalled);
+    }
+
     /**
      * Test that the needed requirements are met
      */