diff --git a/wp-admin/post.php b/wp-admin/post.php
index 341341a26f..e29156b3ae 100644
--- a/wp-admin/post.php
+++ b/wp-admin/post.php
@@ -66,7 +66,7 @@ case 'edit':
 
 	$post_ID = $p = (int) $_GET['post'];
 
-	if ( !user_can_edit_post($user_ID, $post_ID) )
+	if ( !current_user_can('edit_post', $post_ID) )
 		die ( __('You are not allowed to edit this post.') );
 
 	if ( !user_can_edit_post($user_ID, $post_ID) )
diff --git a/wp-admin/upgrade-functions.php b/wp-admin/upgrade-functions.php
index 2a7262a7a4..4653ef5d3d 100644
--- a/wp-admin/upgrade-functions.php
+++ b/wp-admin/upgrade-functions.php
@@ -226,8 +226,11 @@ function upgrade_160() {
 			update_usermeta( $user->ID, 'last_name', $wpdb->escape($user->user_lastname) );
 		if ( !empty( $user->user_nickname ) )
 			update_usermeta( $user->ID, 'nickname', $wpdb->escape($user->user_nickname) );
-		if ( !empty( $user->user_level ) )
+		if ( !empty( $user->user_level ) ) {
 			update_usermeta( $user->ID, $table_prefix . 'user_level', $user->user_level );
+			$role = translate_level_to_role($user->user_level);
+			update_usermeta( $user->ID, $table_prefix . 'capabilities', array($role => true) );
+		}
 		if ( !empty( $user->user_icq ) )
 			update_usermeta( $user->ID, 'icq', $wpdb->escape($user->user_icq) );
 		if ( !empty( $user->user_aim ) )
@@ -749,4 +752,27 @@ function make_site_theme() {
 	}
 	return $template;
 }
+
+function translate_level_to_role($level) {
+	switch ($level) {
+	case 10:
+	case 9:
+	case 8:
+		return 'publisher';
+	case 7:
+	case 6:
+	case 5:
+		return 'managing_editor';
+	case 4:
+	case 3:
+		return 'copy_editor';
+	case 2:
+		return 'staff_writer';
+	case 1:
+		return 'freelancer';
+	case 0:
+		return 'visitor';
+	}
+}
+
 ?>
\ No newline at end of file
diff --git a/wp-admin/upgrade-schema.php b/wp-admin/upgrade-schema.php
index d545fa83d5..8ffa6d5fda 100644
--- a/wp-admin/upgrade-schema.php
+++ b/wp-admin/upgrade-schema.php
@@ -216,6 +216,8 @@ function populate_options() {
 	// 1.5.1
 	add_option('use_trackback', 0);
 
+	populate_roles();
+
 	// Delete unused options
 	$unusedoptions = array ('blodotgsping_url', 'bodyterminator', 'emailtestonly', 'phoneemail_separator', 'smilies_directory', 'subjectprefix', 'use_bbcode', 'use_blodotgsping', 'use_phoneemail', 'use_quicktags', 'use_weblogsping', 'weblogs_cache_file', 'use_preview', 'use_htmltrans', 'smilies_directory', 'fileupload_allowedusers', 'use_phoneemail', 'default_post_status', 'default_post_category', 'archive_mode', 'time_difference', 'links_minadminlevel', 'links_use_adminlevels', 'links_rating_type', 'links_rating_char', 'links_rating_ignore_zero', 'links_rating_single_image', 'links_rating_image0', 'links_rating_image1', 'links_rating_image2', 'links_rating_image3', 'links_rating_image4', 'links_rating_image5', 'links_rating_image6', 'links_rating_image7', 'links_rating_image8', 'links_rating_image9', 'weblogs_cacheminutes', 'comment_allowed_tags', 'search_engine_friendly_urls', 'default_geourl_lat', 'default_geourl_lon', 'use_default_geourl', 'weblogs_xml_url');
 	foreach ($unusedoptions as $option) :
@@ -229,4 +231,80 @@ function populate_options() {
 	endforeach;
 }
 
+function populate_roles() {
+	global $table_prefix;
+
+	$roles = array ('administrator' =>
+									array('name' => __('Administrator'),
+											'capabilities' => array(
+												'edit_posts' => true,
+												'edit_others_posts' => true,
+												'edit_published_posts' => true,
+												'publish_posts' => true,
+												'edit_pages' => true,
+												'manage_categories' => true,
+												'manage_links' => true,
+												'upload_images' => true,
+												'manage_options' => true,
+												'switch_themes' => true,
+												'edit_themes' => true,
+												'activate_plugins' => true,
+												'edit_plugins' => true,
+												'edit_users' => true,
+												'edit_files' => true,
+												'read' => true,
+												'level_10' => true,
+												'level_9' => true,
+												'level_8' => true
+												)),
+
+									'editor' =>
+									array('name' => __('Editor'),
+											'capabilities' => array(
+												'edit_posts' => true,
+												'edit_others_posts' => true,
+												'edit_published_posts' => true,
+												'publish_posts' => true,
+												'edit_pages' => true,
+												'manage_categories' => true,
+												'manage_links' => true,
+												'upload_images' => true,
+												'read' => true,
+												'level_7' => true,
+												'level_6' => true,
+												'level_5' => true
+												)),
+
+									'author' =>
+									array('name' => __('Author'),
+											'capabilities' => array(
+												'edit_posts' => true,
+												'publish_posts' => true,
+												'upload_images' => true,
+												'read' => true,
+												'level_2' => true
+												)),
+
+									'contributor' =>
+									array('name' => __('Contributor'),
+											'capabilities' => array(
+												'edit_posts' => true,
+												'read' => true,
+												'level_1' => true
+												)),
+											
+									'subscriber' =>
+									array('name' => __('Subscriber'),
+											'capabilities' => array(
+												'read' => true,
+												'level_0' => true
+												)),
+
+									'inactive' =>
+									array('name' => __('Inactive'),
+												'capabilities' => array())
+									);
+
+	add_option($table_prefix . 'user_roles', $roles);
+}
 ?>
diff --git a/wp-includes/capabilities.php b/wp-includes/capabilities.php
new file mode 100644
index 0000000000..af5fb5879d
--- /dev/null
+++ b/wp-includes/capabilities.php
@@ -0,0 +1,263 @@
+<?php
+
+class WP_Roles {
+	var $roles;
+
+	var $role_objects = array();
+	var $role_names = array();
+	var $role_key;
+
+	function WP_Roles() {
+		global $table_prefix;
+		$this->role_key = $table_prefix . 'user_roles';
+
+		$this->roles = get_option($this->role_key);
+
+		if ( empty($this->roles) )
+			return;
+
+		foreach ($this->roles as $role => $data) {
+			$this->role_objects[$role] = new WP_Role($role, $this->roles[$role]['capabilities']);
+			$this->role_names[$role] = $this->roles[$role]['name'];
+		}
+	}
+
+	function add_role($role, $capabilities, $display_name) {
+		$this->roles[$role] = array('name' => $display_name,
+																'capabilities' => $capabilities);
+		update_option($this->role_key, $this->roles);
+		$this->role_objects[$role] = new WP_Role($role, $capabilities);
+		$this->role_names[$role] = $display_name;
+	}
+	
+	function remove_role($role) {
+		if ( ! isset($this->role_objects[$role]) )
+			return;
+		
+		unset($this->role_objects[$role]);
+		unset($this->role_names[$role]);
+		unset($this->roles[$role]);
+		
+		update_option($this->role_key, $this->roles);
+	}
+
+	function add_cap($role, $cap, $grant) {
+		$this->roles[$role]['capabilities'][$cap] = $grant;
+		update_option($this->role_key, $this->roles);
+	}
+
+	function remove_cap($role, $cap) {
+		unset($this->roles[$role]['capabilities'][$cap]);
+		update_option($this->role_key, $this->roles);
+	}
+
+	function &get_role($role) {
+		if ( isset($this->role_objects[$role]) )
+			return $this->role_objects[$role];
+		else
+			return null;
+	}
+
+	function get_names() {
+		return $this->role_names;
+	}
+
+	function is_role($caps)
+	{
+		return empty($this->role_names[$cap]);
+	}	
+}
+
+class WP_Role {
+	var $name;
+	var $capabilities;
+
+	function WP_Role($role, $capabilities) {
+		$this->name = $role;
+		$this->capabilities = $capabilities;
+	}
+
+	function add_cap($cap, $grant) {
+		global $wp_roles;
+
+		$this->capabilities[$cap] = $grant;
+		$wp_roles->add_cap($this->name, $cap);
+	}
+
+	function remove_cap($cap) {
+		global $wp_roles;
+
+		unset($this->capabilities[$cap]);
+		$wp_roles->remove_cap($this->name, $cap);
+	}
+
+	function has_cap($cap) {
+		if ( !empty($this->capabilities[$cap]) )
+			return $this->capabilities[$cap];
+		else
+			return false;
+	}
+
+}
+
+class WP_User {
+	var $data;
+	var $id;
+	var $caps;
+	var $cap_key;
+	var $roles;
+	var $allcaps;
+
+	function WP_User($id) {
+		global $wp_roles, $table_prefix;
+		$this->id = $id;
+		$this->data = get_userdata($id);
+		$this->cap_key = $table_prefix . 'capabilities';
+		$this->caps = &$this->data->{$this->cap_key};
+		$this->get_role_caps();
+	}
+	
+	function get_role_caps() {
+		global $wp_roles;
+		//Filter out caps that are not role names and assign to $this->roles
+		if(is_array($this->caps))
+			$this->roles = array_filter($this->caps, array(&$wp_roles, 'is_role'));
+
+		//Build $allcaps from role caps, overlay user's $caps
+		$this->allcaps = array();
+		foreach($this->roles as $role => $value) {
+			$role = $wp_roles->get_role($role);
+			$this->allcaps = array_merge($this->allcaps, $role->capabilities);
+		}
+		$this->allcaps = array_merge($this->allcaps, $this->caps);
+	}
+	
+	function add_role($role) {
+		$this->caps[$role] = true;
+		update_usermeta($this->id, $this->cap_key, $this->caps);
+		$this->get_role_caps();
+		$this->update_user_level_from_caps();
+	}
+	
+	function remove_role($role) {
+		if(!empty($this->roles[$role]) && (count($this->roles) > 1))
+		unset($this->caps[$cap]);
+		update_usermeta($this->id, $this->cap_key, $this->caps);
+		$this->get_role_caps();
+	}
+	
+	function set_role($role) {
+		foreach($this->roles as $oldrole => $value)
+			unset($this->caps[$oldrole]);
+		$this->caps[$role] = true;
+		$this->roles = array($role => true);
+		update_usermeta($this->id, $this->cap_key, $this->caps);
+		$this->get_role_caps();
+		$this->update_user_level_from_caps();
+	}
+
+	function level_reduction($max, $item) {
+	    if(preg_match('/^level_(10|[0-9])$/i', $item, $matches)) {
+	        $level = intval($matches[1]);
+	        return max($max, $level);
+	    } else {
+	        return $max;
+	    }
+	}
+	
+	function update_user_level_from_caps() {
+	    global $table_prefix;
+	    $this->data->user_level = array_reduce(array_keys($this->allcaps), 	array(&$this, 'level_reduction'), 0);
+	    update_usermeta($this->id, $table_prefix.'user_level', $this->data->user_level);
+	}
+	
+	function add_cap($cap, $grant = true) {
+		$this->caps[$cap] = $grant;
+		update_usermeta($this->id, $this->cap_key, $this->caps);
+	}
+
+	function remove_cap($cap) {
+		if(!empty($this->roles[$role])) return;
+		unset($this->caps[$cap]);
+		update_usermeta($this->id, $this->cap_key, $this->caps);
+	}
+	
+	//has_cap(capability_or_role_name) or
+	//has_cap('edit_post', post_id)
+	function has_cap($cap) {
+		global $wp_roles;
+
+		if ( is_numeric($cap) )
+			$cap = $this->translate_level_to_cap($cap);
+		
+		$args = array_slice(func_get_args(), 1);
+		$args = array_merge(array($cap, $this->id), $args);
+		$caps = call_user_func_array('map_meta_cap', $args);
+		// Must have ALL requested caps
+		foreach ($caps as $cap) {
+			//echo "Checking cap $cap<br/>";
+			if(empty($this->allcaps[$cap]) || !$this->allcaps[$cap])
+				return false;
+		}
+
+		return true;
+	}
+
+	function translate_level_to_cap($level) {
+		return 'level_' . $level;
+	}
+
+}
+
+// Map meta capabilities to primitive capabilities.
+function map_meta_cap($cap, $user_id) {
+	$args = array_slice(func_get_args(), 2);
+	$caps = array();
+
+	switch ($cap) {
+		// edit_post breaks down to edit_posts, edit_published_posts, or
+		// edit_others_posts
+	case 'edit_post':
+		$author_data = get_userdata($user_id);
+		//echo "post ID: {$args[0]}<br/>";
+		$post = get_post($args[0]);
+		$post_author_data = get_userdata($post->post_author);
+		//echo "current user id : $user_id, post author id: " . $post_author_data->ID . "<br/>";
+		// If the user is the author...
+		if ($user_id == $post_author_data->ID) {
+			// If the post is published...
+			if ($post->post_status == 'publish')
+				$caps[] = 'edit_published_posts';
+			else
+				// If the post is draft...
+				$caps[] = 'edit_posts';
+		} else {
+			// The user is trying to edit someone else's post.
+			$caps[] = 'edit_others_posts';
+			// The post is published, extra cap required.
+			if ($post->post_status == 'publish')
+				$caps[] = 'edit_published_posts';
+		}
+		break;
+	default:
+		// If no meta caps match, return the original cap.
+		$caps[] = $cap;
+	}
+
+	return $caps;
+}
+
+// Capability checking wrapper around the global $current_user object.
+function current_user_can($capability) {
+	global $current_user;
+
+	$args = array_slice(func_get_args(), 1);
+	$args = array_merge(array($capability), $args);
+
+	if ( empty($current_user) )
+		return false;
+
+	return call_user_func_array(array(&$current_user, 'has_cap'), $args);
+}
+
+?>
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index f4641019a9..af027d7d72 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -1218,32 +1218,11 @@ function update_post_caches(&$posts) {
 
 function update_category_cache() {
 	global $cache_categories, $wpdb;
-	$dogs = $wpdb->get_results("SELECT * FROM $wpdb->categories");
-	foreach ($dogs as $catt)
-		$cache_categories[$catt->cat_ID] = $catt;
-}
-
-function update_user_cache() {
-	global $cache_userdata, $wpdb;
-	$level_key = $wpdb->prefix . 'user_level';
-	$user_ids = $wpdb->get_col("SELECT user_id FROM $wpdb->usermeta WHERE meta_key = '$level_key'");
-	$user_ids = join(',', $user_ids);
-	$query = apply_filters('user_cache_query', "SELECT * FROM $wpdb->users WHERE ID IN ($user_ids)");
-	if ( $users = $wpdb->get_results( $query ) ) :
-		foreach ($users as $user) :
-			$metavalues = $wpdb->get_results("SELECT meta_key, meta_value FROM $wpdb->usermeta WHERE user_id = '$user->ID'");
-			foreach ( $metavalues as $meta ) {
-				$user->{$meta->meta_key} = $meta->meta_value;
-				// We need to set user_level from meta, not row
-				if ( $wpdb->prefix . 'user_level' == $meta->meta_key )
-					$user->user_level = $meta->meta_value;
-			}
-
-			$cache_userdata[$user->ID] = $user;
-			$cache_userdata[$user->user_login] =& $cache_userdata[$user->ID];
-		endforeach;
+	if($dogs = $wpdb->get_results("SELECT * FROM $wpdb->categories")):
+		foreach ($dogs as $catt)
+			$cache_categories[$catt->cat_ID] = $catt;
 		return true;
-	else : 
+	else:
 		return false;
 	endif;
 }
@@ -1959,11 +1938,38 @@ function nocache_headers() {
 	@ header('Pragma: no-cache');
 }
 
+function get_usermeta( $user_id, $meta_key = '') {
+	global $wpdb;
+	$user_id = (int) $user_id;
+
+	if ( !empty($meta_key) ) {
+		$meta_key = preg_replace('|a-z0-9_|i', '', $meta_key);
+		$metas = $wpdb->get_results("SELECT * FROM $wpdb->usermeta WHERE user_id = '$user_id' AND meta_key = '$meta_key'");
+	} else {
+		$metas = $wpdb->get_results("SELECT * FROM $wpdb->usermeta WHERE user_id = '$user_id'");
+	}
+
+	foreach ($metas as $index => $meta) {
+		@ $value = unserialize($meta->meta_key);
+		if ($value !== FALSE)
+			$metas[$index]->meta_key = $value;			
+	}
+
+	if ( !empty($meta_key) )
+		return $metas[0];
+	else
+		return $metas;
+}
+
 function update_usermeta( $user_id, $meta_key, $meta_value ) {
 	global $wpdb;
 	if ( !is_numeric( $user_id ) )
 		return false;
 	$meta_key = preg_replace('|a-z0-9_|i', '', $meta_key);
+
+	if ( is_array($meta_value) || is_object($meta_value) )
+		$meta_value = serialize($meta_value);
+
 	$cur = $wpdb->get_row("SELECT * FROM $wpdb->usermeta WHERE user_id = '$user_id' AND meta_key = '$meta_key'");
 	if ( !$cur ) {
 		$wpdb->query("INSERT INTO $wpdb->usermeta ( user_id, meta_key, meta_value )
@@ -1991,4 +1997,4 @@ function plugin_basename($file) {
 	return preg_replace('/^.*wp-content[\\\\\/]plugins[\\\\\/]/', '', $file);
 }
 
-?>
\ No newline at end of file
+?>
diff --git a/wp-includes/pluggable-functions.php b/wp-includes/pluggable-functions.php
index de2851c7ed..4d25ffd781 100644
--- a/wp-includes/pluggable-functions.php
+++ b/wp-includes/pluggable-functions.php
@@ -19,7 +19,9 @@ function get_currentuserinfo() {
 	$user_url    = $userdata->user_url;
 	$user_pass_md5 = md5($userdata->user_pass);
 	$user_identity = $userdata->display_name;
-	$current_user  = $userdata;
+
+	if ( empty($current_user) )
+		$current_user = new WP_User($user_ID);
 }
 endif;
 
@@ -29,7 +31,7 @@ function get_userdata( $user_id ) {
 	$user_id = (int) $user_id;
 	if ( $user_id == 0 )
 		return false;
-
+		
 	if ( isset( $cache_userdata[$user_id] ) ) 
 		return $cache_userdata[$user_id];
 
@@ -39,7 +41,11 @@ function get_userdata( $user_id ) {
 	$metavalues = $wpdb->get_results("SELECT meta_key, meta_value FROM $wpdb->usermeta WHERE user_id = '$user_id'");
 
 	foreach ( $metavalues as $meta ) {
-		$user->{$meta->meta_key} = $meta->meta_value;
+		@ $value = unserialize($meta->meta_value);
+		if ($value === FALSE)
+			$value = $meta->meta_value;
+		$user->{$meta->meta_key} = $value;
+
 		// We need to set user_level from meta, not row
 		if ( $wpdb->prefix . 'user_level' == $meta->meta_key )
 			$user->user_level = $meta->meta_value;
diff --git a/wp-settings.php b/wp-settings.php
index 890401d977..c45cb4827a 100644
--- a/wp-settings.php
+++ b/wp-settings.php
@@ -74,7 +74,7 @@ require (ABSPATH . WPINC . '/default-filters.php');
 require_once (ABSPATH . WPINC . '/wp-l10n.php');
 
 $wpdb->hide_errors();
-if ( !update_user_cache() && (!strstr($_SERVER['PHP_SELF'], 'install.php') && !defined('WP_INSTALLING')) ) {
+if ( !update_category_cache() && (!strstr($_SERVER['PHP_SELF'], 'install.php') && !defined('WP_INSTALLING')) ) {
 	if ( strstr($_SERVER['PHP_SELF'], 'wp-admin') )
 		$link = 'install.php';
 	else
@@ -85,6 +85,7 @@ $wpdb->show_errors();
 
 require (ABSPATH . WPINC . '/functions-formatting.php');
 require (ABSPATH . WPINC . '/functions-post.php');
+require (ABSPATH . WPINC . '/capabilities.php');
 require (ABSPATH . WPINC . '/classes.php');
 require (ABSPATH . WPINC . '/template-functions-general.php');
 require (ABSPATH . WPINC . '/template-functions-links.php');
@@ -160,6 +161,7 @@ register_shutdown_function('shutdown_action_hook');
 $wp_query = new WP_Query();
 $wp_rewrite = new WP_Rewrite();
 $wp = new WP();
+$wp_roles = new WP_Roles();
 
 // Everything is loaded and initialized.
 do_action('init');