diff --git a/activemodel/lib/active_model/mass_assignment_security.rb b/activemodel/lib/active_model/mass_assignment_security.rb
index be48415739f4a84cffda865aa3b7398a6835707f..e3299331759dccb77d32fb61ebcbfb6658a168b2 100644
--- a/activemodel/lib/active_model/mass_assignment_security.rb
+++ b/activemodel/lib/active_model/mass_assignment_security.rb
@@ -24,10 +24,7 @@ module MassAssignmentSecurity
     #     include ActiveModel::MassAssignmentSecurity
     #
     #     attr_accessible :first_name, :last_name
-    #
-    #     def self.admin_accessible_attributes
-    #       accessible_attributes + [ :plan_id ]
-    #     end
+    #     attr_accessible :first_name, :last_name, :plan_id, :as => :admin
     #
     #     def update
     #       ...
@@ -37,19 +34,18 @@ module MassAssignmentSecurity
     #
     #     protected
     #
-    #     def account_params
-    #       sanitize_for_mass_assignment(params[:account])
-    #     end
-    #
-    #     def mass_assignment_authorizer
-    #       admin ? admin_accessible_attributes : super
+    #     def scope
+    #       scope = admin ? :admin : :default
+    #       sanitize_for_mass_assignment(params[:account], scope)
     #     end
     #
     #   end
     #
     module ClassMethods
       # Attributes named in this macro are protected from mass-assignment
-      # whenever attributes are sanitized before assignment.
+      # whenever attributes are sanitized before assignment. A scope for the
+      # attributes is optional, if no scope is provided then :default is used.
+      # A scope can be defined by using the :as option.
       #
       # Mass-assignment to these attributes will simply be ignored, to assign
       # to them you can use direct writer methods. This is meant to protect
@@ -60,36 +56,58 @@ module ClassMethods
       #     include ActiveModel::MassAssignmentSecurity
       #
       #     attr_accessor :name, :credit_rating
-      #     attr_protected :credit_rating
       #
-      #     def attributes=(values)
-      #       sanitize_for_mass_assignment(values).each do |k, v|
+      #     attr_protected :credit_rating, :last_login
+      #     attr_protected :last_login, :as => :admin
+      #
+      #     def assign_attributes(values, options = {})
+      #       sanitize_for_mass_assignment(values, options[:as]).each do |k, v|
       #         send("#{k}=", v)
       #       end
       #     end
       #   end
       #
+      # When using a :default scope :
+      #
       #   customer = Customer.new
-      #   customer.attributes = { "name" => "David", "credit_rating" => "Excellent" }
+      #   customer.assign_attributes({ "name" => "David", "credit_rating" => "Excellent", :last_login => 1.day.ago }, :as => :default)
       #   customer.name          # => "David"
       #   customer.credit_rating # => nil
+      #   customer.last_login    # => nil
       #
       #   customer.credit_rating = "Average"
       #   customer.credit_rating # => "Average"
       #
+      # And using the :admin scope :
+      #
+      #   customer = Customer.new
+      #   customer.assign_attributes({ "name" => "David", "credit_rating" => "Excellent", :last_login => 1.day.ago }, :as => :admin)
+      #   customer.name          # => "David"
+      #   customer.credit_rating # => "Excellent"
+      #   customer.last_login    # => nil
+      #
       # To start from an all-closed default and enable attributes as needed,
       # have a look at +attr_accessible+.
       #
       # Note that using <tt>Hash#except</tt> or <tt>Hash#slice</tt> in place of +attr_protected+
       # to sanitize attributes won't provide sufficient protection.
-      def attr_protected(*names)
-        self._protected_attributes = self.protected_attributes + names
+      def attr_protected(*args)
+        options = args.extract_options!
+        scope = options[:as] || :default
+
+        self._protected_attributes        = protected_attributes_configs.dup
+        self._protected_attributes[scope] = self.protected_attributes(scope) + args
+
         self._active_authorizer = self._protected_attributes
       end
 
       # Specifies a white list of model attributes that can be set via
       # mass-assignment.
       #
+      # Like +attr_protected+, a scope for the attributes is optional,
+      # if no scope is provided then :default is used. A scope can be defined by
+      # using the :as option.
+      #
       # This is the opposite of the +attr_protected+ macro: Mass-assignment
       # will only set attributes in this list, to assign to the rest of
       # attributes you can use direct writer methods. This is meant to protect
@@ -102,57 +120,90 @@ def attr_protected(*names)
       #     include ActiveModel::MassAssignmentSecurity
       #
       #     attr_accessor :name, :credit_rating
+      #
       #     attr_accessible :name
+      #     attr_accessible :name, :credit_rating, :as => :admin
       #
-      #     def attributes=(values)
-      #       sanitize_for_mass_assignment(values).each do |k, v|
+      #     def assign_attributes(values, options = {})
+      #       sanitize_for_mass_assignment(values, options[:as]).each do |k, v|
       #         send("#{k}=", v)
       #       end
       #     end
       #   end
       #
+      # When using a :default scope :
+      #
       #   customer = Customer.new
-      #   customer.attributes = { :name => "David", :credit_rating => "Excellent" }
+      #   customer.assign_attributes({ "name" => "David", "credit_rating" => "Excellent", :last_login => 1.day.ago }, :as => :default)
       #   customer.name          # => "David"
       #   customer.credit_rating # => nil
       #
       #   customer.credit_rating = "Average"
       #   customer.credit_rating # => "Average"
       #
+      # And using the :admin scope :
+      #
+      #   customer = Customer.new
+      #   customer.assign_attributes({ "name" => "David", "credit_rating" => "Excellent", :last_login => 1.day.ago }, :as => :admin)
+      #   customer.name          # => "David"
+      #   customer.credit_rating # => "Excellent"
+      #
       # Note that using <tt>Hash#except</tt> or <tt>Hash#slice</tt> in place of +attr_accessible+
       # to sanitize attributes won't provide sufficient protection.
-      def attr_accessible(*names)
-        self._accessible_attributes = self.accessible_attributes + names
+      def attr_accessible(*args)
+        options = args.extract_options!
+        scope = options[:as] || :default
+
+        self._accessible_attributes        = accessible_attributes_configs.dup
+        self._accessible_attributes[scope] = self.accessible_attributes(scope) + args
+
         self._active_authorizer = self._accessible_attributes
       end
 
-      def protected_attributes
-        self._protected_attributes ||= BlackList.new(attributes_protected_by_default).tap do |w|
-          w.logger = self.logger if self.respond_to?(:logger)
-        end
+      def protected_attributes(scope = :default)
+        protected_attributes_configs[scope]
       end
 
-      def accessible_attributes
-        self._accessible_attributes ||= WhiteList.new.tap { |w| w.logger = self.logger if self.respond_to?(:logger) }
+      def accessible_attributes(scope = :default)
+        accessible_attributes_configs[scope]
       end
 
-      def active_authorizer
-        self._active_authorizer ||= protected_attributes
+      def active_authorizers
+        self._active_authorizer ||= protected_attributes_configs
       end
+      alias active_authorizer active_authorizers
 
       def attributes_protected_by_default
         []
       end
+
+      private
+
+      def protected_attributes_configs
+        self._protected_attributes ||= begin
+          default_black_list = BlackList.new(attributes_protected_by_default).tap do |w|
+            w.logger = self.logger if self.respond_to?(:logger)
+          end
+          Hash.new(default_black_list)
+        end
+      end
+
+      def accessible_attributes_configs
+        self._accessible_attributes ||= begin
+          default_white_list = WhiteList.new.tap { |w| w.logger = self.logger if self.respond_to?(:logger) }
+          Hash.new(default_white_list)
+        end
+      end
     end
 
   protected
 
-    def sanitize_for_mass_assignment(attributes)
-      mass_assignment_authorizer.sanitize(attributes)
+    def sanitize_for_mass_assignment(attributes, scope = :default)
+      mass_assignment_authorizer(scope).sanitize(attributes)
     end
 
-    def mass_assignment_authorizer
-      self.class.active_authorizer
+    def mass_assignment_authorizer(scope = :default)
+      self.class.active_authorizer[scope]
     end
   end
 end
diff --git a/activemodel/test/cases/mass_assignment_security_test.rb b/activemodel/test/cases/mass_assignment_security_test.rb
index f84e55e8d97dd33f9cfd96cf976d5b4398b00090..b22ce874ea65dae920c2f528654e09e0e8a84585 100644
--- a/activemodel/test/cases/mass_assignment_security_test.rb
+++ b/activemodel/test/cases/mass_assignment_security_test.rb
@@ -10,10 +10,27 @@ def test_attribute_protection
     assert_equal expected, sanitized
   end
 
+  def test_only_moderator_scope_attribute_accessible
+    user = SpecialUser.new
+    expected = { "name" => "John Smith", "email" => "john@smith.com" }
+    sanitized = user.sanitize_for_mass_assignment(expected.merge("admin" => true), :moderator)
+    assert_equal expected, sanitized
+
+    sanitized = user.sanitize_for_mass_assignment({ "name" => "John Smith", "email" => "john@smith.com", "admin" => true })
+    assert_equal({}, sanitized)
+  end
+
   def test_attributes_accessible
     user = Person.new
     expected = { "name" => "John Smith", "email" => "john@smith.com" }
-    sanitized = user.sanitize_for_mass_assignment(expected.merge("super_powers" => true))
+    sanitized = user.sanitize_for_mass_assignment(expected.merge("admin" => true))
+    assert_equal expected, sanitized
+  end
+
+  def test_admin_scoped_attributes_accessible
+    user = Person.new
+    expected = { "name" => "John Smith", "email" => "john@smith.com", "admin" => true }
+    sanitized = user.sanitize_for_mass_assignment(expected.merge("super_powers" => true), :admin)
     assert_equal expected, sanitized
   end
 
@@ -26,20 +43,30 @@ def test_attributes_protected_by_default
 
   def test_mass_assignment_protection_inheritance
     assert_blank LoosePerson.accessible_attributes
-    assert_equal Set.new([ 'credit_rating', 'administrator']), LoosePerson.protected_attributes
+    assert_equal Set.new(['credit_rating', 'administrator']), LoosePerson.protected_attributes
+
+    assert_blank LoosePerson.accessible_attributes
+    assert_equal Set.new(['credit_rating']), LoosePerson.protected_attributes(:admin)
 
     assert_blank LooseDescendant.accessible_attributes
-    assert_equal Set.new([ 'credit_rating', 'administrator', 'phone_number']), LooseDescendant.protected_attributes
+    assert_equal Set.new(['credit_rating', 'administrator', 'phone_number']), LooseDescendant.protected_attributes
 
     assert_blank LooseDescendantSecond.accessible_attributes
-    assert_equal Set.new([ 'credit_rating', 'administrator', 'phone_number', 'name']), LooseDescendantSecond.protected_attributes,
+    assert_equal Set.new(['credit_rating', 'administrator', 'phone_number', 'name']), LooseDescendantSecond.protected_attributes,
       'Running attr_protected twice in one class should merge the protections'
 
     assert_blank TightPerson.protected_attributes - TightPerson.attributes_protected_by_default
-    assert_equal Set.new([ 'name', 'address' ]), TightPerson.accessible_attributes
+    assert_equal Set.new(['name', 'address']), TightPerson.accessible_attributes
+
+    assert_blank TightPerson.protected_attributes(:admin) - TightPerson.attributes_protected_by_default
+    assert_equal Set.new(['name', 'address', 'admin']), TightPerson.accessible_attributes(:admin)
 
     assert_blank TightDescendant.protected_attributes - TightDescendant.attributes_protected_by_default
-    assert_equal Set.new([ 'name', 'address', 'phone_number' ]), TightDescendant.accessible_attributes
+    assert_equal Set.new(['name', 'address', 'phone_number']), TightDescendant.accessible_attributes
+
+    assert_blank TightDescendant.protected_attributes(:admin) - TightDescendant.attributes_protected_by_default
+    assert_equal Set.new(['name', 'address', 'admin', 'super_powers']), TightDescendant.accessible_attributes(:admin)
+
   end
 
   def test_mass_assignment_multiparameter_protector
diff --git a/activemodel/test/cases/secure_password_test.rb b/activemodel/test/cases/secure_password_test.rb
index c455cf57b3adfe98aeaf02701cca97eeef16de02..6950c3be1f79535a321002ac5739f6cf1ed7c2ab 100644
--- a/activemodel/test/cases/secure_password_test.rb
+++ b/activemodel/test/cases/secure_password_test.rb
@@ -45,13 +45,14 @@ class SecurePasswordTest < ActiveModel::TestCase
   end
 
   test "visitor#password_digest should be protected against mass assignment" do
-    assert Visitor.active_authorizer.kind_of?(ActiveModel::MassAssignmentSecurity::BlackList)
-    assert Visitor.active_authorizer.include?(:password_digest)
+    assert Visitor.active_authorizers[:default].kind_of?(ActiveModel::MassAssignmentSecurity::BlackList)
+    assert Visitor.active_authorizers[:default].include?(:password_digest)
   end
 
   test "Administrator's mass_assignment_authorizer should be WhiteList" do
-    assert Administrator.active_authorizer.kind_of?(ActiveModel::MassAssignmentSecurity::WhiteList)
-    assert !Administrator.active_authorizer.include?(:password_digest)
-    assert Administrator.active_authorizer.include?(:name)
+    active_authorizer = Administrator.active_authorizers[:default]
+    assert active_authorizer.kind_of?(ActiveModel::MassAssignmentSecurity::WhiteList)
+    assert !active_authorizer.include?(:password_digest)
+    assert active_authorizer.include?(:name)
   end
 end
diff --git a/activemodel/test/models/mass_assignment_specific.rb b/activemodel/test/models/mass_assignment_specific.rb
index 2a8fe170c2286cc5c2dc1901a313eb805cf24936..53b37369ff62b96942fb24ceee145f4b3642f089 100644
--- a/activemodel/test/models/mass_assignment_specific.rb
+++ b/activemodel/test/models/mass_assignment_specific.rb
@@ -5,9 +5,17 @@ class User
   public :sanitize_for_mass_assignment
 end
 
+class SpecialUser
+  include ActiveModel::MassAssignmentSecurity
+  attr_accessible :name, :email, :as => :moderator
+
+  public :sanitize_for_mass_assignment
+end
+
 class Person
   include ActiveModel::MassAssignmentSecurity
   attr_accessible :name, :email
+  attr_accessible :name, :email, :admin, :as => :admin
 
   public :sanitize_for_mass_assignment
 end
@@ -32,6 +40,7 @@ class Task
 class LoosePerson
   include ActiveModel::MassAssignmentSecurity
   attr_protected :credit_rating, :administrator
+  attr_protected :credit_rating, :as => :admin
 end
 
 class LooseDescendant < LoosePerson
@@ -46,6 +55,7 @@ class LooseDescendantSecond< LoosePerson
 class TightPerson
   include ActiveModel::MassAssignmentSecurity
   attr_accessible :name, :address
+  attr_accessible :name, :address, :admin, :as => :admin
 
   def self.attributes_protected_by_default
     ["mobile_number"]
@@ -54,4 +64,5 @@ def self.attributes_protected_by_default
 
 class TightDescendant < TightPerson
   attr_accessible :phone_number
+  attr_accessible :super_powers, :as => :admin
 end
\ No newline at end of file