Index: wp-includes/comment-template.php
===================================================================
--- wp-includes/comment-template.php	(revision 8954)
+++ wp-includes/comment-template.php	(working copy)
@@ -850,7 +850,7 @@
 
 	$args = wp_parse_args($args, $defaults);
 
-	if ( 0 == $args['depth'] || $args['max_depth'] < $args['depth'] )
+	if ( 0 == $args['depth'] || $args['max_depth'] <= $args['depth'] )
 		return;
 
 	extract($args, EXTR_SKIP);
@@ -973,15 +973,34 @@
  * @uses Walker_Comment
  *
  * @param $args string|array Formatting options
-	* @param $comments array Optional array of comment objects.  Defaults to $wp_query->comments
+ * @param $comments array Optional array of comment objects.  Defaults to $wp_query->comments
  */
 function wp_list_comments($args = array(), $comments = null ) {
 	global $wp_query;
 
-	$defaults = array('walker' => null, 'depth' => 3, 'style' => 'ul', 'callback' => null, 'end-callback' => null, 'type' => 'all');
+	$defaults = array('walker' => null, 'depth' => '', 'style' => 'ul', 'callback' => null, 'end-callback' => null, 'type' => 'all',
+		'page' => get_query_var('cpage'), 'per_page' => '');
 
 	$r = wp_parse_args( $args, $defaults );
 
+	if ( '' === $r['per_page'] && get_option('page_comments') )
+		$r['per_page'] = get_query_var('comments_per_page');
+
+	if ( empty($r['per_page']) ) {
+		$r['page'] = 0;
+	} else {
+		$r['page'] = intval($r['page']);
+		if ( empty($r['page']) )
+			$r['page'] = 1;
+	}
+
+	if ( '' === $r['depth'] ) {
+		if ( get_option('thread_comments') )
+			$r['depth'] = get_option('thread_comments_depth');
+		else
+			$r['depth'] = -1;
+	}
+
 	extract( $r, EXTR_SKIP );
 
 	if ( empty($walker) )
@@ -995,19 +1014,25 @@
 				$wp_query->comments_by_type = &separate_comments($wp_query->comments);
 			if ( empty($wp_query->comments_by_type[$type]) )
 				return;
-			return $walker->walk($wp_query->comments_by_type[$type], $depth, $r);
+			$walker->paged_walk($wp_query->comments_by_type[$type], $depth, $page, $per_page, $r);
+			$wp_query->max_num_comment_pages = $walker->max_pages;
+			return;
 		}
-		$walker->walk($wp_query->comments, $depth, $r);
+		$walker->paged_walk($wp_query->comments, $depth, $page, $per_page, $r);
+		$wp_query->max_num_comment_pages = $walker->max_pages;
 	} else {
 		if ( empty($comments) )
 			return;
 		if ( 'all' != $type ) {
-			$comments_by_type = separate_comments($comments);
+			$comments_by_type = &separate_comments($comments);
 			if ( empty($comments_by_type[$type]) )
 				return;
-			return $walker->walk($comments_by_type[$type], $depth, $r);
+			$walker->paged_walk($comments_by_type[$type], $depth, $page, $per_page, $r);
+			$wp_query->max_num_comment_pages = $walker->max_pages;
+			return;
 		}
-		$walker->walk($comments, $depth, $r);
+		$walker->paged_walk($comments, $depth, $page, $per_page, $r);
+		$wp_query->max_num_comment_pages = $walker->max_pages;
 	}
 }
 
Index: wp-includes/query.php
===================================================================
--- wp-includes/query.php	(revision 8954)
+++ wp-includes/query.php	(working copy)
@@ -844,6 +844,15 @@
 	var $max_num_pages = 0;
 
 	/**
+	 * The amount of comment pages.
+	 *
+	 * @since 2.7.0
+	 * @access public
+	 * @var int
+	 */
+	var $max_num_comment_pages = 0;
+
+	/**
 	 * Set if query is single post.
 	 *
 	 * @since 1.5.0
@@ -1612,6 +1621,9 @@
 		else if ( $q['posts_per_page'] == 0 )
 			$q['posts_per_page'] = 1;
 
+		if ( !isset($q['comments_per_page']) || $q['comments_per_page'] == 0 )
+			$q['comments_per_page'] = get_option('comments_per_page');
+
 		if ( $this->is_home && (empty($this->query) || $q['preview'] == 'true') && ( 'page' == get_option('show_on_front') ) && get_option('page_on_front') ) {
 			$this->is_page = true;
 			$this->is_home = false;
Index: wp-includes/link-template.php
===================================================================
--- wp-includes/link-template.php	(revision 8954)
+++ wp-includes/link-template.php	(working copy)
@@ -793,6 +793,84 @@
 	}
 }
 
+function get_comments_pagenum_link($pagenum = 1) {
+	global $wp_rewrite;
+
+	$pagenum = (int) $pagenum;
+
+	$request = remove_query_arg( 'cpage' );
+
+	$home_root = parse_url(get_option('home'));
+	$home_root = ( isset($home_root['path']) ) ? $home_root['path'] : '';
+	$home_root = preg_quote( trailingslashit( $home_root ), '|' );
+
+	$request = preg_replace('|^'. $home_root . '|', '', $request);
+	$request = preg_replace('|^/+|', '', $request);
+
+	$base = trailingslashit( get_bloginfo( 'home' ) );
+
+	if ( $pagenum > 1 ) {
+		$result = add_query_arg( 'cpage', $pagenum, $base . $request );
+	} else {
+		$result = $base . $request;
+	}
+
+	$result = apply_filters('get_comments_pagenum_link', $result);
+
+	return $result;
+}
+
+function next_comments_link($label='', $max_page = 0) {
+	global $wp_query;
+
+	if ( !is_singular() )
+		return;
+
+	$page = get_query_var('cpage');
+	
+	if ( !$page )
+		$page = 1;
+
+	if ( !$page )
+		$page = 1;
+
+	$nextpage = intval($page) + 1;
+
+	if ( empty($max_page) )
+		$max_page = $wp_query->max_num_comment_pages;
+
+	if ( $nextpage > $max_page )
+		return;
+
+	if ( empty($label) )
+		$label = __('&raquo; Newer Comments');
+
+	echo '<a href="' . clean_url(get_comments_pagenum_link($nextpage));
+	$attr = apply_filters( 'next_comments_link_attributes', '' );
+	echo "\" $attr>". preg_replace('/&([^#])(?![a-z]{1,8};)/', '&#038;$1', $label) .'</a>';
+}
+
+function previous_comments_link($label='') {
+	global $wp_query;
+
+	if ( !is_singular() )
+		return;
+
+	$page = get_query_var('cpage');
+
+	if ( $page <= 1 )
+		return;
+
+	$nextpage = intval($page) - 1;
+
+	if ( empty($label) )
+		$label = __('&laquo; Older Comments');
+
+	echo '<a href="' . clean_url(get_comments_pagenum_link($nextpage));
+	$attr = apply_filters( 'previous_comments_link_attributes', '' );
+	echo "\" $attr>". preg_replace('/&([^#])(?![a-z]{1,8};)/', '&#038;$1', $label) .'</a>';
+}
+
 function get_shortcut_link() {
 	$link = "javascript:
 			var d=document,
Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 8954)
+++ wp-includes/formatting.php	(working copy)
@@ -1820,6 +1820,9 @@
 		case 'default_category':
 		case 'default_email_category':
 		case 'default_link_category':
+		case 'close_comments_days_old':
+		case 'comments_per_page':
+		case 'thread_comments_depth':
 			$value = abs((int) $value);
 			break;
 
Index: wp-includes/classes.php
===================================================================
--- wp-includes/classes.php	(revision 8954)
+++ wp-includes/classes.php	(working copy)
@@ -26,7 +26,7 @@
 	 * @access public
 	 * @var array
 	 */
-	var $public_query_vars = array('m', 'p', 'posts', 'w', 'cat', 'withcomments', 'withoutcomments', 's', 'search', 'exact', 'sentence', 'debug', 'calendar', 'page', 'paged', 'more', 'tb', 'pb', 'author', 'order', 'orderby', 'year', 'monthnum', 'day', 'hour', 'minute', 'second', 'name', 'category_name', 'tag', 'feed', 'author_name', 'static', 'pagename', 'page_id', 'error', 'comments_popup', 'attachment', 'attachment_id', 'subpost', 'subpost_id', 'preview', 'robots', 'taxonomy', 'term');
+	var $public_query_vars = array('m', 'p', 'posts', 'w', 'cat', 'withcomments', 'withoutcomments', 's', 'search', 'exact', 'sentence', 'debug', 'calendar', 'page', 'paged', 'more', 'tb', 'pb', 'author', 'order', 'orderby', 'year', 'monthnum', 'day', 'hour', 'minute', 'second', 'name', 'category_name', 'tag', 'feed', 'author_name', 'static', 'pagename', 'page_id', 'error', 'comments_popup', 'attachment', 'attachment_id', 'subpost', 'subpost_id', 'preview', 'robots', 'taxonomy', 'term', 'cpage');
 
 	/**
 	 * Private query variables.
@@ -36,7 +36,7 @@
 	 * @since 2.0.0
 	 * @var array
 	 */
-	var $private_query_vars = array('offset', 'posts_per_page', 'posts_per_archive_page', 'what_to_show', 'showposts', 'nopaging', 'post_type', 'post_status', 'category__in', 'category__not_in', 'category__and', 'tag__in', 'tag__not_in', 'tag__and', 'tag_slug__in', 'tag_slug__and', 'tag_id', 'post_mime_type', 'perm');
+	var $private_query_vars = array('offset', 'posts_per_page', 'posts_per_archive_page', 'what_to_show', 'showposts', 'nopaging', 'post_type', 'post_status', 'category__in', 'category__not_in', 'category__and', 'tag__in', 'tag__not_in', 'tag__and', 'tag_slug__in', 'tag_slug__and', 'tag_id', 'post_mime_type', 'perm', 'comments_per_page');
 
 	/**
 	 * Extra query variables set by the user.
@@ -731,6 +731,15 @@
 	var $db_fields;
 
 	/**
+	 * Max number of pages walked by the paged walker 
+	 *
+	 * @since 2.7.0
+	 * @var int
+	 * @access protected
+	 */
+	var $max_pages = 1;
+
+	/**
 	 * Starts the list before the elements are added.
 	 *
 	 * Additional parameters are used in child classes. The args parameter holds
@@ -947,7 +956,7 @@
 	function paged_walk( $elements, $max_depth, $page_num, $per_page ) {
 
 		/* sanity check */
-		if ( empty($elements) || $max_depth < 0 )
+		if ( empty($elements) || $max_depth < -1 )
 			return '';
 
 		$args = array_slice( func_get_args(), 4 );
@@ -956,6 +965,38 @@
 		$id_field = $this->db_fields['id'];
 		$parent_field = $this->db_fields['parent'];
 
+		$count = -1;
+		if ( -1 == $max_depth )
+			$total_top = count( $elements );
+		if ( $page_num < 1 || $per_page < 0  ) {
+			// No paging
+			$paging = false;
+			$start = 0;
+			if ( -1 == $max_depth )
+				$end = $total_top;
+			$this->max_pages = 1;
+		} else {
+			$paging = true;
+			$start = ( (int)$page_num - 1 ) * (int)$per_page;
+			$end   = $start + $per_page;
+			if ( -1 == $max_depth )
+				$this->max_pages = ceil($total_top / $per_page);
+		}
+
+		// flat display
+		if ( -1 == $max_depth ) {
+			$empty_array = array();
+			foreach ( $elements as $e ) {
+				$count++;
+				if ( $count < $start )
+					continue;
+				if ( $count >= $end )
+					break;
+				$this->display_element( $e, $empty_array, 1, 0, $args, $output );
+			}
+			return $output;
+		}
+
 		/*
 		 * seperate elements into two buckets: top level and children elements
 		 * children_elements is two dimensional array, eg.
@@ -970,16 +1011,11 @@
 				$children_elements[ $e->$parent_field ][] = $e;
 		}
 
-		$count = -1;
 		$total_top = count( $top_level_elements );
-		if ( $page_num < 1 || $per_page < 0  ) {
-			$start = 0;
-			$end = $total_top;
-		} else {
-			$start = ( (int)$page_num - 1 ) * (int)$per_page;
-			$end   = $start + $per_page;
-		}
 
+		if ( $paging )
+			$this->max_pages = ceil($total_top / $per_page);
+
 		foreach( $top_level_elements as $e ){
 			$count++;
 
@@ -996,7 +1032,7 @@
 			$this->display_element( $e, $children_elements, $max_depth, 0, $args, $output );
 		}
 
-		if ( $end >= $total_top && count( $children_elements ) > 0 ){
+		if ( $end >= $total_top && count( $children_elements ) > 0 ) {
 			$empty_array = array();
 			foreach ( $children_elements as $orphans )
 				foreach( $orphans as $op )
@@ -1030,7 +1066,8 @@
 		foreach ( (array)$children_elements[$id] as $child )
 			$this->unset_children( $child, $children_elements );
 
-		unset( $children_elements[$id] );
+		if ( isset($children_elements[$id]) )
+			unset( $children_elements[$id] );
 
 	}
 }
Index: wp-content/themes/default/comments.php
===================================================================
--- wp-content/themes/default/comments.php	(revision 8954)
+++ wp-content/themes/default/comments.php	(working copy)
@@ -15,9 +15,12 @@
 	<h3 id="comments"><?php comments_number('No Responses', 'One Response', '% Responses' );?> to &#8220;<?php the_title(); ?>&#8221;</h3>
 
 	<ol class="commentlist">
-	<?php wp_list_comments($comments); ?>
+	<?php wp_list_comments(); ?>
 	</ol>
-
+	<div class="navigation">
+		<div class="alignleft"><?php previous_comments_link() ?></div>
+		<div class="alignright"><?php next_comments_link() ?></div>
+	</div>
  <?php else : // this is displayed if there are no comments so far ?>
 
 	<?php if ('open' == $post->comment_status) : ?>
Index: wp-admin/options-discussion.php
===================================================================
--- wp-admin/options-discussion.php	(revision 8954)
+++ wp-admin/options-discussion.php	(working copy)
@@ -40,6 +40,14 @@
 <input name="close_comments_for_old_posts" type="checkbox" id="close_comments_for_old_posts" value="1" <?php checked('1', get_option('close_comments_for_old_posts')); ?> />
 <?php _e('Close comments on articles older than') ?></label> <?php printf(__('%s days'), '<input name="close_comments_days_old" type="text" id="close_comments_days_old" value="' . attribute_escape(get_option('close_comments_days_old')) . '" size="3" />') ?>
 <br />
+<label for="thread_comments">
+<input name="thread_comments" type="checkbox" id="thread_comments" value="1" <?php checked('1', get_option('thread_comments')); ?> />
+<?php _e('Group replies into threads') ?></label> <?php printf(__('%s levels deep'), '<input name="thread_comments_depth" type="text" id="thread_comments_depth" value="' . attribute_escape(get_option('thread_comments_depth')) . '" size="3" />') ?>
+<br />
+<label for="page_comments">
+<input name="page_comments" type="checkbox" id="page_comments" value="1" <?php checked('1', get_option('page_comments')); ?> />
+<?php _e('Break comments into pages with') ?></label> <?php printf(__('%s comments per page'), '<input name="comments_per_page" type="text" id="comments_per_page" value="' . attribute_escape(get_option('comments_per_page')) . '" size="3" />') ?>
+<br />
 <small><em><?php echo '(' . __('These settings may be overridden for individual articles.') . ')'; ?></em></small>
 </fieldset></td>
 </tr>
Index: wp-admin/options.php
===================================================================
--- wp-admin/options.php	(revision 8954)
+++ wp-admin/options.php	(working copy)
@@ -23,7 +23,7 @@
 
 $whitelist_options = array(
 	'general' => array('blogname', 'blogdescription', 'admin_email', 'users_can_register', 'gmt_offset', 'date_format', 'time_format', 'start_of_week', 'comment_registration', 'default_role' ),
-	'discussion' => array( 'default_pingback_flag', 'default_ping_status', 'default_comment_status', 'comments_notify', 'moderation_notify', 'comment_moderation', 'require_name_email', 'comment_whitelist', 'comment_max_links', 'moderation_keys', 'blacklist_keys', 'show_avatars', 'avatar_rating', 'close_comments_for_old_posts', 'close_comments_days_old' ),
+	'discussion' => array( 'default_pingback_flag', 'default_ping_status', 'default_comment_status', 'comments_notify', 'moderation_notify', 'comment_moderation', 'require_name_email', 'comment_whitelist', 'comment_max_links', 'moderation_keys', 'blacklist_keys', 'show_avatars', 'avatar_rating', 'close_comments_for_old_posts', 'close_comments_days_old', 'thread_comments', 'thread_comments_depth', 'page_comments', 'comments_per_page' ),
 	'misc' => array( 'hack_file', 'use_linksupdate', 'uploads_use_yearmonth_folders', 'upload_path' ),
 	'media' => array( 'thumbnail_size_w', 'thumbnail_size_h', 'thumbnail_crop', 'medium_size_w', 'medium_size_h', 'large_size_w', 'large_size_h', 'image_default_size', 'image_default_align', 'image_default_link_type' ),
 	'privacy' => array( 'blog_public' ),