diff --git a/activemodel/CHANGELOG.md b/activemodel/CHANGELOG.md
index a8f470397b3f81cd5bb1d1ba8ca1e784baff25c9..1916c3439a7c2ad83955de48e6bbd0be2aa80d2e 100644
--- a/activemodel/CHANGELOG.md
+++ b/activemodel/CHANGELOG.md
@@ -1,5 +1,11 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Changed inclusion and exclusion validators to accept a symbol for `:in` option.
+
+    This allows to use dynamic inclusion/exclusion values using methods, besides the current lambda/proc support.
+
+    *Gabriel Sobrinho*
+
 *   `AM::Validation#validates` ability to pass custom exception to `:strict` option.
 
     *Bogdan Gusiev*
diff --git a/activemodel/lib/active_model/validations/clusivity.rb b/activemodel/lib/active_model/validations/clusivity.rb
index 643a6f2b7cff55c05a3aaf0f56410864a588bde3..cf1415b6c2a39aa4e2d7c914119006aa078e9af9 100644
--- a/activemodel/lib/active_model/validations/clusivity.rb
+++ b/activemodel/lib/active_model/validations/clusivity.rb
@@ -3,11 +3,11 @@
 module ActiveModel
   module Validations
     module Clusivity #:nodoc:
-      ERROR_MESSAGE = "An object with the method #include? or a proc or lambda is required, " <<
+      ERROR_MESSAGE = "An object with the method #include? or a proc, lambda or symbol is required, " <<
                       "and must be supplied as the :in (or :within) option of the configuration hash"
 
       def check_validity!
-        unless [:include?, :call].any?{ |method| delimiter.respond_to?(method) }
+        unless delimiter.respond_to?(:include?) || delimiter.respond_to?(:call) || delimiter.respond_to?(:to_sym)
           raise ArgumentError, ERROR_MESSAGE
         end
       end
@@ -15,7 +15,14 @@ def check_validity!
     private
 
       def include?(record, value)
-        exclusions = delimiter.respond_to?(:call) ? delimiter.call(record) : delimiter
+        exclusions = if delimiter.respond_to?(:call)
+                       delimiter.call(record)
+                     elsif delimiter.respond_to?(:to_sym)
+                       record.send(delimiter)
+                     else
+                       delimiter
+                     end
+
         exclusions.send(inclusion_method(exclusions), value)
       end
 
diff --git a/activemodel/lib/active_model/validations/exclusion.rb b/activemodel/lib/active_model/validations/exclusion.rb
index dc3368c5694d9c2cb586605eef50f7efab72e174..3ec552c372945230fc1a8f7604f88092e8df9055 100644
--- a/activemodel/lib/active_model/validations/exclusion.rb
+++ b/activemodel/lib/active_model/validations/exclusion.rb
@@ -24,11 +24,12 @@ module HelperMethods
       #     validates_exclusion_of :format, in: %w( mov avi ), message: "extension %{value} is not allowed"
       #     validates_exclusion_of :password, in: ->(person) { [person.username, person.first_name] },
       #                            message: 'should not be the same as your username or first name'
+      #     validates_exclusion_of :karma, in: :reserved_karmas
       #   end
       #
       # Configuration options:
       # * <tt>:in</tt> - An enumerable object of items that the value shouldn't
-      #   be part of. This can be supplied as a proc or lambda which returns an
+      #   be part of. This can be supplied as a proc, lambda or symbol which returns an
       #   enumerable. If the enumerable is a range the test is performed with
       # * <tt>:within</tt> - A synonym(or alias) for <tt>:in</tt>
       #   <tt>Range#cover?</tt>, otherwise with <tt>include?</tt>.
diff --git a/activemodel/lib/active_model/validations/inclusion.rb b/activemodel/lib/active_model/validations/inclusion.rb
index c2835c550bcaa629099d9ba171484ca27f440fa6..babc8982daf787e26eb31ed22d1bfa5fabe79002 100644
--- a/activemodel/lib/active_model/validations/inclusion.rb
+++ b/activemodel/lib/active_model/validations/inclusion.rb
@@ -23,11 +23,12 @@ module HelperMethods
       #     validates_inclusion_of :age, in: 0..99
       #     validates_inclusion_of :format, in: %w( jpg gif png ), message: "extension %{value} is not included in the list"
       #     validates_inclusion_of :states, in: ->(person) { STATES[person.country] }
+      #     validates_inclusion_of :karma, in: :available_karmas
       #   end
       #
       # Configuration options:
       # * <tt>:in</tt> - An enumerable object of available items. This can be
-      #   supplied as a proc or lambda which returns an enumerable. If the
+      #   supplied as a proc, lambda or symbol which returns an enumerable. If the
       #   enumerable is a range the test is performed with <tt>Range#cover?</tt>,
       #   otherwise with <tt>include?</tt>.
       # * <tt>:within</tt> - A synonym(or alias) for <tt>:in</tt>
diff --git a/activemodel/test/cases/validations/exclusion_validation_test.rb b/activemodel/test/cases/validations/exclusion_validation_test.rb
index baccf72ecb023c1248f036bbeafdb1a5267ce5b4..9f916dbfdd7d1081d9b029ff7fe94450da56189e 100644
--- a/activemodel/test/cases/validations/exclusion_validation_test.rb
+++ b/activemodel/test/cases/validations/exclusion_validation_test.rb
@@ -64,4 +64,26 @@ def test_validates_exclusion_of_with_lambda
     t.title = "wasabi"
     assert t.valid?
   end
+
+  def test_validates_inclusion_of_with_symbol
+    Person.validates_exclusion_of :karma, :in => :reserved_karmas
+
+    p = Person.new
+    p.karma = "abe"
+
+    def p.reserved_karmas
+      %w(abe)
+    end
+
+    assert p.invalid?
+    assert_equal ["is reserved"], p.errors[:karma]
+
+    def p.reserved_karmas
+      %w()
+    end
+
+    assert p.valid?
+  ensure
+    Person.reset_callbacks(:validate)
+  end
 end
diff --git a/activemodel/test/cases/validations/inclusion_validation_test.rb b/activemodel/test/cases/validations/inclusion_validation_test.rb
index c57fa75faf34ffadd2dd59dbb73aba48a1eaab82..92638f8e707b900e71bb962a5ca1fce79bf0575b 100644
--- a/activemodel/test/cases/validations/inclusion_validation_test.rb
+++ b/activemodel/test/cases/validations/inclusion_validation_test.rb
@@ -96,4 +96,26 @@ def test_validates_inclusion_of_with_lambda
     t.title = "elephant"
     assert t.valid?
   end
+
+  def test_validates_inclusion_of_with_symbol
+    Person.validates_inclusion_of :karma, :in => :available_karmas
+
+    p = Person.new
+    p.karma = "Lifo"
+
+    def p.available_karmas
+      %w()
+    end
+
+    assert p.invalid?
+    assert_equal ["is not included in the list"], p.errors[:karma]
+
+    def p.available_karmas
+      %w(Lifo)
+    end
+
+    assert p.valid?
+  ensure
+    Person.reset_callbacks(:validate)
+  end
 end