diff --git a/lib/jekyll-archives.rb b/lib/jekyll-archives.rb
index 18cde72..a671110 100644
--- a/lib/jekyll-archives.rb
+++ b/lib/jekyll-archives.rb
@@ -31,14 +31,15 @@ def initialize(config = nil)
 
       def generate(site)
         @site = site
-        @posts = site.posts
-        @archives = []
 
+        # Archive the posts collection by default
+        @site.posts.metadata["archive"] = true
+
+        @archives = []
         @site.config["jekyll-archives"] = @config
 
         read
         @site.pages.concat(@archives)
-
         @site.config["archives"] = @archives
       end
 
@@ -81,43 +82,72 @@ def read_dates
       def enabled?(archive)
         @config["enabled"] == true || @config["enabled"] == "all" || if @config["enabled"].is_a? Array
                                                                        @config["enabled"].include? archive
+                                                                     end
+      end
+
+      def date_attr_hash(date_format, date_posts)
+        hash = Hash.new { |h, key| h[key] = [] }
+
+        date_posts.each do |p|
+          hash[p.date.strftime(date_format)] << p
         end
+
+        hash.values.each { |posts| posts.sort!.reverse! }
+        hash
+      end
+
+      def doc_attr_hash(doc_attr)
+        hash = Hash.new { |h, key| h[key] = [] }
+
+        @site.collections.each do |name, collection|
+          if collection.metadata["archive"]
+            collection.docs.each do |d|
+              case doc_attr
+              when "tags"
+                d.data["tags"].each { |t| hash[t] << d } if d.data["tags"]
+              when "categories"
+                d.data["categories"].each { |t| hash[t] << d } if d.data["categories"]
+              when "years"
+                hash[d.date.strftime("%Y")] << d
+              end
+            end
+          end
+        end
+
+        hash.values.each { |posts| posts.sort!.reverse! }
+        hash
       end
 
       def tags
-        @site.post_attr_hash("tags")
+        if Jekyll::VERSION >= "3.0.0"
+          doc_attr_hash("tags")
+        else
+          @site.post_attr_hash("tags")
+        end
       end
 
       def categories
-        @site.post_attr_hash("categories")
+        if Jekyll::VERSION >= "3.0.0"
+          doc_attr_hash("categories")
+        else
+          @site.post_attr_hash("categories")
+        end
       end
 
-      # Custom `post_attr_hash` method for years
       def years
-        hash = Hash.new { |h, key| h[key] = [] }
-
-        # In Jekyll 3, Collection#each should be called on the #docs array directly.
         if Jekyll::VERSION >= "3.0.0"
-          @posts.docs.each { |p| hash[p.date.strftime("%Y")] << p }
+          doc_attr_hash("years")
         else
-          @posts.each { |p| hash[p.date.strftime("%Y")] << p }
+          date_attr_hash("%Y", @site.posts)
         end
-        hash.values.each { |posts| posts.sort!.reverse! }
-        hash
       end
 
       def months(year_posts)
-        hash = Hash.new { |h, key| h[key] = [] }
-        year_posts.each { |p| hash[p.date.strftime("%m")] << p }
-        hash.values.each { |posts| posts.sort!.reverse! }
-        hash
+        date_attr_hash("%m", year_posts)
       end
 
       def days(month_posts)
-        hash = Hash.new { |h, key| h[key] = [] }
-        month_posts.each { |p| hash[p.date.strftime("%d")] << p }
-        hash.values.each { |posts| posts.sort!.reverse! }
-        hash
+        date_attr_hash("%d", month_posts)
       end
     end
   end
diff --git a/lib/jekyll-archives/archive.rb b/lib/jekyll-archives/archive.rb
index 66585bf..fce2fb5 100644
--- a/lib/jekyll-archives/archive.rb
+++ b/lib/jekyll-archives/archive.rb
@@ -18,10 +18,14 @@ class Archive < Jekyll::Page
       # Initialize a new Archive page
       #
       # site  - The Site object.
-      # title - The name of the tag/category or a Hash of the year/month/day in case of date.
-      #           e.g. { :year => 2014, :month => 08 } or "my-category" or "my-tag".
-      # type  - The type of archive. Can be one of "year", "month", "day", "category", or "tag"
-      # posts - The array of posts that belong in this archive.
+      # title - The name of the tag/category or a Hash of
+      #         the year/month/day in case of date.
+      #         e.g. { :year => 2014, :month => 08 } or
+      #         "my-category" or "my-tag".
+      # type  - The type of archive. Can be one of "year",
+      #         "month", "day", "category", or "tag"
+      # posts - The array of posts that belong in this
+      #         archive.
       def initialize(site, title, type, posts)
         @site   = site
         @posts  = posts
@@ -62,8 +66,9 @@ def layout
         end
       end
 
-      # Returns a hash of URL placeholder names (as symbols) mapping to the
-      # desired placeholder replacements. For details see "url.rb".
+      # Returns a hash of URL placeholder names (as symbols)
+      # mapping to the desired placeholder replacements.
+      # For details see "url.rb".
       def url_placeholders
         if @title.is_a? Hash
           @title.merge(:type => @type)
@@ -72,7 +77,8 @@ def url_placeholders
         end
       end
 
-      # The generated relative url of this page. e.g. /about.html.
+      # The generated relative url of this page. e.g.
+      # /about.html.
       #
       # Returns the String url.
       def url
@@ -89,10 +95,11 @@ def permalink
         data && data.is_a?(Hash) && data["permalink"]
       end
 
-      # Produce a title object suitable for Liquid based on type of archive.
+      # Produce a title object suitable for Liquid based on
+      # type of archive.
       #
-      # Returns a String (for tag and category archives) and nil for
-      # date-based archives.
+      # Returns a String (for tag and category archives) and
+      # nil for date-based archives.
       def title
         @title if @title.is_a? String
       end
@@ -107,7 +114,8 @@ def date
         end
       end
 
-      # Obtain the write path relative to the destination directory
+      # Obtain the write path relative to the destination
+      # directory.
       #
       # Returns the destination relative path String.
       def relative_path