diff --git a/lib/zodiac.rb b/lib/zodiac.rb
index 63728de..9b24461 100644
--- a/lib/zodiac.rb
+++ b/lib/zodiac.rb
@@ -12,3 +12,4 @@ def self.each_sign(&block)
 
 require 'zodiac/date'
 require 'zodiac/activerecord'
+require 'zodiac/mongoid'
diff --git a/lib/zodiac/mongoid.rb b/lib/zodiac/mongoid.rb
new file mode 100644
index 0000000..c11fae2
--- /dev/null
+++ b/lib/zodiac/mongoid.rb
@@ -0,0 +1,69 @@
+module Zodiac
+  module Mongoid
+    module InstanceMethods
+      def zodiac_sign
+        raise 'You should call #zodiac_reader in your class for this to work' unless self.class.respond_to?(:date_for_zodiac)
+        self.send(self.class.date_for_zodiac).try(:zodiac_sign)
+      end
+
+      Zodiac.each_sign do |symbol, integer|
+        method_name = "#{symbol}?"
+        define_method(method_name) do
+          raise 'You should call #zodiac_reader in your class for this to work' unless self.class.respond_to?(:date_for_zodiac)
+          self.send(self.class.date_for_zodiac).try(method_name)
+        end
+      end
+    private
+      def update_sign_id
+        sign_id_method  = "#{self.class.zodiac_sign_id_field}="
+        new_sign_id     = send(self.class.date_for_zodiac).try(:zodiac_sign_id)
+        send(sign_id_method, new_sign_id)
+      end
+    end
+
+    module ClassMethods
+      attr_accessor :date_for_zodiac, :zodiac_sign_id_field
+
+      def zodiac_reader(dob_attribute, options = {:sign_id_attribute => :zodiac_sign_id})
+        @date_for_zodiac = dob_attribute
+        @zodiac_sign_id_field = options[:sign_id_attribute]
+
+        # if the zodiac_sign_id attribute is present, we should update the sign attribute before each save
+        # and define some scopes
+        columns = self.fields.collect { |field| field[0].to_s }
+        if columns.include?(@zodiac_sign_id_field.to_s)
+          "registering Zodiac before_save"
+          self.before_save do |object|
+            object.send(:update_sign_id)
+          end
+
+          # Person.by_zodiac(7 || :libra) == Person.where(:zodiac_sign_id => 7)
+          scope :by_zodiac, lambda { |sign|
+            case sign
+            when Symbol
+              where(self.zodiac_sign_id_field => Zodiac::Finder::SIGN_IDS[sign])
+            when Fixnum
+              where(self.zodiac_sign_id_field => sign)
+            else
+              raise ArgumentError, "Invalid attribute type #{sign.class} for #{self}.by_zodiac"
+            end
+          }
+
+          # Person.gemini == Person.by_zodiac(3)
+          Zodiac.each_sign do |symbol, integer|
+            scope symbol, by_zodiac(integer)
+          end
+        end
+      end
+    end
+
+    def self.included(base)
+      base.send :include, InstanceMethods
+      base.extend ClassMethods
+    end
+  end
+end
+
+if defined?(::Mongoid)
+  Mongoid::Document.send(:include, Zodiac::Mongoid)
+end