diff --git a/src/Composer/EventDispatcher/EventDispatcher.php b/src/Composer/EventDispatcher/EventDispatcher.php
index 3762529e7..acf8d2f2c 100644
--- a/src/Composer/EventDispatcher/EventDispatcher.php
+++ b/src/Composer/EventDispatcher/EventDispatcher.php
@@ -165,11 +165,25 @@ class EventDispatcher
         $className::$methodName($event);
     }
 
+    /**
+     * Add a listener for a particular event
+     *
+     * @param string   $eventName The event name - typically a constant
+     * @param Callable $listener  A callable expecting an event argument
+     * @param integer  $priority  A higher value represents a higher priority
+     */
     protected function addListener($eventName, $listener, $priority = 0)
     {
         $this->listeners[$eventName][$priority][] = $listener;
     }
 
+    /**
+     * Adds object methods as listeners for the events in getSubscribedEvents
+     *
+     * @see EventSubscriberInterface
+     *
+     * @param EventSubscriberInterface $subscriber
+     */
     public function addSubscriber(EventSubscriberInterface $subscriber)
     {
         foreach ($subscriber->getSubscribedEvents() as $eventName => $params) {
@@ -185,6 +199,12 @@ class EventDispatcher
         }
     }
 
+    /**
+     * Retrieves all listeners for a given event
+     *
+     * @param Event $event
+     * @return array All listeners: callables and scripts
+     */
     protected function getListeners(Event $event)
     {
         $scriptListeners = $this->getScriptListeners($event);
@@ -201,6 +221,8 @@ class EventDispatcher
     }
 
     /**
+     * Finds all listeners defined as scripts in the package
+     *
      * @param  Event $event Event object
      * @return array Listeners
      */
diff --git a/src/Composer/Plugin/PluginManager.php b/src/Composer/Plugin/PluginManager.php
index a6956c24e..386de461b 100644
--- a/src/Composer/Plugin/PluginManager.php
+++ b/src/Composer/Plugin/PluginManager.php
@@ -45,6 +45,9 @@ class PluginManager
         $this->io = $io;
     }
 
+    /**
+     * Loads all plugins from currently installed plugin packages
+     */
     public function loadInstalledPlugins()
     {
         $repo = $this->composer->getRepositoryManager()->getLocalRepository();
@@ -59,7 +62,7 @@ class PluginManager
     }
 
     /**
-     * Adds plugin
+     * Adds a plugin, activates it and registers it with the event dispatcher
      *
      * @param PluginInterface $plugin plugin instance
      */
@@ -73,11 +76,25 @@ class PluginManager
         }
     }
 
+    /**
+     * Gets all currently active plugin instances
+     *
+     * @return array plugins
+     */
     public function getPlugins()
     {
         return $this->plugins;
     }
 
+    /**
+     * Recursively generates a map of package names to packages for all deps
+     *
+     * @param Pool             $pool      Package pool of installed packages
+     * @param array            $collected Current state of the map for recursion
+     * @param PackageInterface $package   The package to analyze
+     *
+     * @return array Map of package names to packages
+     */
     protected function collectDependencies(Pool $pool, array $collected, PackageInterface $package)
     {
         $requires = array_merge(
@@ -96,6 +113,16 @@ class PluginManager
         return $collected;
     }
 
+    /**
+     * Resolves a package link to a package in the installed pool
+     *
+     * Since dependencies are already installed this should always find one.
+     *
+     * @param Pool $pool Pool of installed packages only
+     * @param Link $link Package link to look up
+     *
+     * @return PackageInterface|null The found package
+     */
     protected function lookupInstalledPackage(Pool $pool, Link $link)
     {
         $packages = $pool->whatProvides($link->getTarget(), $link->getConstraint());
@@ -103,6 +130,14 @@ class PluginManager
         return (!empty($packages)) ? $packages[0] : null;
     }
 
+    /**
+     * Register a plugin package, activate it etc.
+     *
+     * If it's of type composer-installer it is registered as an installer
+     * instead for BC
+     *
+     * @param PackageInterface $package
+     */
     public function registerPackage(PackageInterface $package)
     {
         $oldInstallerPlugin = ($package->getType() === 'composer-installer');
@@ -149,6 +184,12 @@ class PluginManager
         }
     }
 
+    /**
+     * Retrieves the path a package is installed to.
+     *
+     * @param PackageInterface $package
+     * @return string Install path
+     */
     public function getInstallPath(PackageInterface $package)
     {
         $targetDir = $package->getTargetDir();
@@ -156,6 +197,14 @@ class PluginManager
         return $this->getPackageBasePath($package) . ($targetDir ? '/'.$targetDir : '');
     }
 
+    /**
+     * Retrieves the base path a package gets installed into.
+     *
+     * Does not take targetDir into account.
+     *
+     * @param PackageInterface $package
+     * @return string Base path
+     */
     protected function getPackageBasePath(PackageInterface $package)
     {
         $vendorDir = rtrim($this->composer->getConfig()->get('vendor-dir'), '/');
diff --git a/src/Composer/Plugin/PreFileDownloadEvent.php b/src/Composer/Plugin/PreFileDownloadEvent.php
index 94621a5c2..847477e10 100644
--- a/src/Composer/Plugin/PreFileDownloadEvent.php
+++ b/src/Composer/Plugin/PreFileDownloadEvent.php
@@ -37,11 +37,9 @@ class PreFileDownloadEvent extends Event
     /**
      * Constructor.
      *
-     * @param string             $name      The event name
-     * @param Composer           $composer  The composer object
-     * @param IOInterface        $io        The IOInterface object
-     * @param boolean            $devMode   Whether or not we are in dev mode
-     * @param OperationInterface $operation The operation object
+     * @param string           $name        The event name
+     * @param RemoteFilesystem $rfs
+     * @param string           $processedUrl
      */
     public function __construct($name, RemoteFilesystem $rfs, $processedUrl)
     {
@@ -53,7 +51,7 @@ class PreFileDownloadEvent extends Event
     /**
      * Returns the remote filesystem
      *
-     * @return OperationInterface
+     * @return RemoteFilesystem
      */
     public function getRemoteFilesystem()
     {
@@ -62,6 +60,8 @@ class PreFileDownloadEvent extends Event
 
     /**
      * Sets the remote filesystem
+     *
+     * @param RemoteFilesystem $rfs
      */
     public function setRemoteFilesystem(RemoteFilesystem $rfs)
     {