diff --git a/doc/faqs/triggers.md b/doc/faqs/triggers.md
new file mode 100644
index 000000000..65fc3c846
--- /dev/null
+++ b/doc/faqs/triggers.md
@@ -0,0 +1,70 @@
+# Triggers
+
+## What is a trigger?
+
+A trigger is an event that runs a script in a static method, defined by a 
+package or project. This event is raised before and after each action (install, 
+update).
+
+
+## Where are the event types defined?
+
+It is in the constant property in `Composer\Trigger\TriggerEvents` class.
+
+
+## How is it defined?
+
+It is defined by adding the `triggers` key in the `extra` key to a project's
+`composer.json` or package's `composer.json`.
+
+It is specified as an associative array of classes with her static method,
+associated with the event's type.
+
+The PSR-0 must be defined, otherwise the trigger will not be triggered.
+
+For any given package:
+
+```json
+{
+    "extra": {
+        "triggers": {
+            "MyVendor\MyPackage\MyClass::myStaticMethod" : "post_install",
+            "MyVendor\MyPackage\MyClass::myStaticMethod2" : "post_update",
+        }
+    },
+    "autoload": {
+        "psr-0": {
+            "MyVendor\MyPackage": ""
+        }
+    }
+}
+```
+
+For any given project:
+```json
+{
+    "extra": {
+        "triggers": {
+            "MyVendor\MyPackage2\MyClass2::myStaticMethod2" : "post_install",
+            "MyVendor\MyPackage2\MyClass2::myStaticMethod3" : "post_update",
+        }
+    },
+    "autoload": {
+        "psr-0": {
+            "MyVendor\MyPackage": "my/folder/path/that/contains/triggers/from/the/root/project"
+        }
+    }
+}
+```
+
+## Informations:
+
+The project's triggers are executed after the package's triggers.
+A declared trigger with non existent file will be ignored.
+
+For example:
+If you declare a trigger for a package pre install, as this trigger isn't 
+downloaded yet, it won't run.
+
+On the other hand, if you declare a pre-update package trigger, as the file 
+already exist, the actual vendor's version of the trigger will be run.
diff --git a/src/Composer/Command/InstallCommand.php b/src/Composer/Command/InstallCommand.php
index bf8bca726..c10b0cfb7 100644
--- a/src/Composer/Command/InstallCommand.php
+++ b/src/Composer/Command/InstallCommand.php
@@ -12,6 +12,10 @@
 
 namespace Composer\Command;
 
+use Composer\Trigger\TriggerEvents;
+
+use Composer\Trigger\TriggerDispatcher;
+
 use Composer\Autoload\AutoloadGenerator;
 use Composer\DependencyResolver;
 use Composer\DependencyResolver\Pool;
@@ -65,6 +69,7 @@ EOT
         $dryRun = (Boolean) $input->getOption('dry-run');
         $verbose = $dryRun || $input->getOption('verbose');
         $composer = $this->getComposer();
+        $dispatcher = new TriggerDispatcher($this->getApplication());
 
         if ($preferSource) {
             $composer->getDownloadManager()->setPreferSource(true);
@@ -82,6 +87,12 @@ EOT
             $pool->addRepository($repository);
         }
 
+        // dispatch pre event
+        if (!$dryRun) {
+            $eventName = $update ? TriggerEvents::PRE_UPDATE : TriggerEvents::PRE_INSTALL;
+            $dispatcher->dispatch($eventName);
+        }
+
         // creating requirements request
         $request = new Request($pool);
         if ($update) {
@@ -177,6 +188,10 @@ EOT
             $output->writeln('<info>Generating autoload files</info>');
             $generator = new AutoloadGenerator;
             $generator->dump($localRepo, $composer->getPackage(), $installationManager, $installationManager->getVendorPath().'/.composer');
+
+            // dispatch post event
+            $eventName = $update ? TriggerEvents::POST_UPDATE : TriggerEvents::POST_INSTALL;
+            $dispatcher->dispatch($eventName);
         }
     }
 
diff --git a/src/Composer/Trigger/GetTriggerEvent.php b/src/Composer/Trigger/GetTriggerEvent.php
new file mode 100644
index 000000000..940e0d0e0
--- /dev/null
+++ b/src/Composer/Trigger/GetTriggerEvent.php
@@ -0,0 +1,108 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Trigger;
+
+use Composer\Console\Application;
+
+/**
+ * The Trigger Event.
+ *
+ * @author François Pluchino <francois.pluchino@opendisplay.com>
+ */
+class GetTriggerEvent
+{
+    /**
+     * @var TriggerDispatcher Dispatcher that dispatched this event
+     */
+    private $dispatcher;
+
+    /**
+     * @var string This event's name
+     */
+    private $name;
+
+    /**
+     * @var Application The application instance
+     */
+    private $application;
+
+    /**
+     * Returns the TriggerDispatcher that dispatches this Event
+     *
+     * @return TriggerDispatcher
+     */
+    public function getDispatcher()
+    {
+        return $this->dispatcher;
+    }
+
+    /**
+     * Stores the TriggerDispatcher that dispatches this Event
+     *
+     * @param TriggerDispatcher $dispatcher
+     */
+    public function setDispatcher(TriggerDispatcher $dispatcher)
+    {
+        $this->dispatcher = $dispatcher;
+    }
+
+    /**
+     * Returns the event's name.
+     *
+     * @return string The event name
+     */
+    public function getName()
+    {
+        return $this->name;
+    }
+
+    /**
+     * Stores the event's name.
+     *
+     * @param string $name The event name
+     */
+    public function setName($name)
+    {
+        $this->name = $name;
+    }
+
+    /**
+     * Returns the application instance.
+     *
+     * @return Application
+     */
+    public function getApplication()
+    {
+        return $this->application;
+    }
+
+    /**
+     * Stores the application instance.
+     *
+     * @param Application $application
+     */
+    public function setApplication(Application $application)
+    {
+        $this->application = $application;
+    }
+
+    /**
+     * Returns the composer instance.
+     *
+     * @return Composer
+     */
+    public function getComposer()
+    {
+        return $this->application->getComposer();
+    }
+}
diff --git a/src/Composer/Trigger/TriggerDispatcher.php b/src/Composer/Trigger/TriggerDispatcher.php
new file mode 100644
index 000000000..ad80d7bd3
--- /dev/null
+++ b/src/Composer/Trigger/TriggerDispatcher.php
@@ -0,0 +1,184 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Trigger;
+
+use Composer\Json\JsonFile;
+use Composer\Repository\FilesystemRepository;
+use Composer\Autoload\ClassLoader;
+use Composer\Package\PackageInterface;
+use Composer\Console\Application;
+use Composer\Composer;
+
+/**
+ * The Trigger Dispatcher.
+ *
+ * Example in command:
+ *     $dispatcher = new TriggerDispatcher($this->getApplication());
+ *     // ...
+ *     $dispatcher->dispatch(TriggerEvents::PRE_INSTALL);
+ *     // ...
+ *
+ * @author François Pluchino <francois.pluchino@opendisplay.com>
+ */
+class TriggerDispatcher
+{
+    protected $application;
+    protected $loader;
+
+    /**
+     * Constructor.
+     *
+     * @param Application $application
+     */
+    public function __construct(Application $application)
+    {
+        $this->application = $application;
+        $this->loader = new ClassLoader();
+    }
+
+    /**
+     * Dispatch the event.
+     *
+     * @param string $eventName The constant in TriggerEvents
+     */
+    public function dispatch($eventName)
+    {
+        $event = new GetTriggerEvent();
+
+        $event->setDispatcher($this);
+        $event->setName($eventName);
+        $event->setApplication($this->application);
+
+        $this->doDispatch($event);
+    }
+
+    /**
+     * Triggers the listeners of an event.
+     *
+     * @param GetTriggerEvent $event The event object to pass to the event handlers/listeners.
+     */
+    protected function doDispatch(GetTriggerEvent $event)
+    {
+        $listeners = $this->getListeners($event);
+
+        foreach ($listeners as $method => $eventType) {
+            if ($eventType === $event->getName()) {
+                $className = substr($method, 0, strpos($method, '::'));
+                $methodName = substr($method, strpos($method, '::') + 2);
+
+                try {
+                    $refMethod = new \ReflectionMethod($className, $methodName);
+
+                    // execute only if all conditions are validates
+                    if ($refMethod->isPublic()
+                            && $refMethod->isStatic()
+                            && !$refMethod->isAbstract()
+                            && 1 === $refMethod->getNumberOfParameters()) {
+                        $className::$methodName($event);
+                    }
+
+                } catch (\ReflectionException $ex) {}//silent execpetion
+            }
+        }
+    }
+
+    /**
+     * Register namespaces in ClassLoader.
+     *
+     * @param GetTriggerEvent $event The event object
+     *
+     * @return array The listener classes with event type
+     */
+    protected function getListeners(GetTriggerEvent $event)
+    {
+        $listeners = array();
+        $composer = $this->application->getComposer();
+        $vendorDir = $composer->getInstallationManager()->getVendorPath(true);
+        $installedFile = $vendorDir . '/.composer/installed.json';
+
+        // get the list of package installed
+        // $composer->getRepositoryManager()->getLocalRepository() not used
+        // because the list is not refreshed for the post event
+        $fsr = new FilesystemRepository(new JsonFile($installedFile));
+        $packages = $fsr->getPackages();
+
+        foreach ($packages as $package) {
+            $listeners = array_merge_recursive($listeners, $this->getListenerClasses($package));
+        }
+
+        // add root package
+        $listeners = array_merge_recursive($listeners, $this->getListenerClasses($composer->getPackage(), true));
+
+        return $listeners;
+    }
+
+    /**
+     * Get listeners and register the namespace on Classloader.
+     *
+     * @param PackageInterface $package The package objet
+     * @param boolean $root             For root composer
+     *
+     * @return array The listener classes with event type
+     */
+    private function getListenerClasses(PackageInterface $package, $root = false)
+    {
+        $composer = $this->application->getComposer();
+        $installDir = $composer->getInstallationManager()->getVendorPath(true)
+                        . '/' . $package->getName();
+        $ex = $package->getExtra();
+        $al = $package->getAutoload();
+        $searchListeners = array();
+        $searchNamespaces = array();
+        $listeners = array();
+        $namespaces = array();
+
+        // get classes
+        if (isset($ex['triggers'])) {
+            foreach ($ex['triggers'] as $method => $event) {
+                $searchListeners[$method] = $event;
+            }
+        }
+
+        // get namespaces
+        if (isset($al['psr-0'])) {
+            foreach ($al['psr-0'] as $ns => $path) {
+                $dir = $root ? realpath('.') : $installDir;
+
+                $path = trim($dir . '/' . $path, '/');
+                $searchNamespaces[$ns] = $path;
+            }
+        }
+
+        // filter class::method have not a namespace registered
+        foreach ($searchNamespaces as $ns => $path) {
+            foreach ($searchListeners as $method => $event) {
+                if (0 === strpos($method, $ns)) {
+                    $listeners[$method] = $event;
+
+                    if (!in_array($ns, array_keys($namespaces))) {
+                        $namespaces[$ns] = $path;
+                    }
+                }
+            }
+        }
+
+        // register namespaces in class loader
+        foreach ($namespaces as $ns => $path) {
+            $this->loader->add($ns, $path);
+        }
+
+        $this->loader->register();
+
+        return $listeners;
+    }
+}
diff --git a/src/Composer/Trigger/TriggerEvents.php b/src/Composer/Trigger/TriggerEvents.php
new file mode 100644
index 000000000..19d542938
--- /dev/null
+++ b/src/Composer/Trigger/TriggerEvents.php
@@ -0,0 +1,65 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Trigger;
+
+/**
+ * The Trigger Events.
+ *
+ * @author François Pluchino <francois.pluchino@opendisplay.com>
+ */
+class TriggerEvents
+{
+    /**
+     * The PRE_INSTALL event occurs at begging installation packages.
+     *
+     * This event allows you to execute a trigger before any other code in the
+     * composer is executed. The event listener method receives a
+     * Composer\Trigger\GetTriggerEvent instance.
+     *
+     * @var string
+     */
+    const PRE_INSTALL = 'pre_install';
+
+    /**
+     * The POST_INSTALL event occurs at end installation packages.
+     *
+     * This event allows you to execute a trigger after any other code in the
+     * composer is executed. The event listener method receives a
+     * Composer\Trigger\GetTriggerEvent instance.
+     *
+     * @var string
+     */
+    const POST_INSTALL = 'post_install';
+
+    /**
+     * The PRE_UPDATE event occurs at begging update packages.
+     *
+     * This event allows you to execute a trigger before any other code in the
+     * composer is executed. The event listener method receives a
+     * Composer\Trigger\GetTriggerEvent instance.
+     *
+     * @var string
+     */
+    const PRE_UPDATE = 'pre_update';
+
+    /**
+     * The POST_UPDATE event occurs at end update packages.
+     *
+     * This event allows you to execute a trigger after any other code in the
+     * composer is executed. The event listener method receives a
+     * Composer\Trigger\GetTriggerEvent instance.
+     *
+     * @var string
+     */
+    const POST_UPDATE = 'post_update';
+}