diff --git a/GETTING_STARTED.md b/GETTING_STARTED.md
index e763ebf..880c197 100644
--- a/GETTING_STARTED.md
+++ b/GETTING_STARTED.md
@@ -762,6 +762,15 @@ factory :user do
 end
 ```
 
+You can define `initialize_with` for all factories by including it in the
+`FactoryGirl.define` block:
+
+```ruby
+FactoryGirl.define do
+  initialize_with { new("Awesome first argument") }
+end
+```
+
 Custom Strategies
 -----------------
 
diff --git a/lib/factory_girl.rb b/lib/factory_girl.rb
index 5d532ff..cc3f270 100644
--- a/lib/factory_girl.rb
+++ b/lib/factory_girl.rb
@@ -50,7 +50,7 @@ module FactoryGirl
 
   class << self
     delegate :factories, :sequences, :traits, :strategies, :callback_names,
-      :to_create, :skip_create, to: :configuration
+      :to_create, :skip_create, :initialize_with, :constructor, to: :configuration
   end
 
   def self.register_factory(factory)
diff --git a/lib/factory_girl/configuration.rb b/lib/factory_girl/configuration.rb
index 687b831..20f24b7 100644
--- a/lib/factory_girl/configuration.rb
+++ b/lib/factory_girl/configuration.rb
@@ -12,8 +12,13 @@ module FactoryGirl
       @definition     = Definition.new
 
       to_create {|instance| instance.save! }
+      initialize_with { new }
     end
 
-    delegate :to_create, :skip_create, to: :@definition
+    delegate :to_create, :skip_create, :constructor, to: :@definition
+
+    def initialize_with(&block)
+      @definition.define_constructor(&block)
+    end
   end
 end
diff --git a/lib/factory_girl/factory.rb b/lib/factory_girl/factory.rb
index dd9ff8d..6218fb2 100644
--- a/lib/factory_girl/factory.rb
+++ b/lib/factory_girl/factory.rb
@@ -34,8 +34,7 @@ module FactoryGirl
       strategy = StrategyCalculator.new(build_strategy).strategy.new
 
       evaluator = evaluator_class.new(build_class, strategy, overrides.symbolize_keys)
-      constructor = compiled_constructor || -> { new }
-      attribute_assigner = AttributeAssigner.new(evaluator, build_class, &constructor)
+      attribute_assigner = AttributeAssigner.new(evaluator, build_class, &compiled_constructor)
 
       evaluation = Evaluation.new(attribute_assigner, compiled_to_create)
       evaluation.add_observer(CallbacksObserver.new(callbacks, evaluator))
@@ -121,7 +120,7 @@ module FactoryGirl
     end
 
     def compiled_constructor
-      @definition.compiled_constructor || parent.compiled_constructor
+      @definition.compiled_constructor || parent.compiled_constructor || FactoryGirl.constructor
     end
 
     private
diff --git a/lib/factory_girl/syntax/default.rb b/lib/factory_girl/syntax/default.rb
index 734bcb5..039467f 100644
--- a/lib/factory_girl/syntax/default.rb
+++ b/lib/factory_girl/syntax/default.rb
@@ -41,6 +41,10 @@ module FactoryGirl
           FactoryGirl.skip_create
         end
 
+        def initialize_with(&block)
+          FactoryGirl.initialize_with(&block)
+        end
+
         def self.run(block)
           new.instance_eval(&block)
         end
diff --git a/spec/acceptance/global_initialize_with_spec.rb b/spec/acceptance/global_initialize_with_spec.rb
new file mode 100644
index 0000000..cebd05e
--- /dev/null
+++ b/spec/acceptance/global_initialize_with_spec.rb
@@ -0,0 +1,82 @@
+require 'spec_helper'
+
+describe 'global initialize_with' do
+  before do
+    define_class('User') do
+      attr_accessor:name
+
+      def initialize(name)
+        @name = name
+      end
+    end
+
+    define_class('Post') do
+      attr_reader :name
+
+      def initialize(name)
+        @name = name
+      end
+    end
+
+    FactoryGirl.define do
+      initialize_with { new("initialize_with") }
+
+      trait :with_initialize_with do
+        initialize_with { new("trait initialize_with") }
+      end
+
+      factory :user do
+        factory :child_user
+
+        factory :child_user_with_trait do
+          with_initialize_with
+        end
+      end
+
+      factory :post do
+        factory :child_post
+
+        factory :child_post_with_trait do
+          with_initialize_with
+        end
+      end
+    end
+  end
+
+  it 'handles base initialize_with' do
+    FactoryGirl.build(:user).name.should == 'initialize_with'
+    FactoryGirl.build(:post).name.should == 'initialize_with'
+  end
+
+  it 'handles child initialize_with' do
+    FactoryGirl.build(:child_user).name.should == 'initialize_with'
+    FactoryGirl.build(:child_post).name.should == 'initialize_with'
+  end
+
+  it 'handles child initialize_with with trait' do
+    FactoryGirl.build(:child_user_with_trait).name.should == 'trait initialize_with'
+    FactoryGirl.build(:child_post_with_trait).name.should == 'trait initialize_with'
+  end
+
+  it 'handles inline trait override' do
+    FactoryGirl.build(:child_user, :with_initialize_with).name.should == 'trait initialize_with'
+    FactoryGirl.build(:child_post, :with_initialize_with).name.should == 'trait initialize_with'
+  end
+
+  it 'uses initialize_with globally across FactoryGirl.define' do
+    define_class('Company') do
+      attr_reader :name
+
+      def initialize(name)
+        @name = name
+      end
+    end
+
+    FactoryGirl.define do
+      factory :company
+    end
+
+    FactoryGirl.build(:company).name.should == 'initialize_with'
+    FactoryGirl.build(:company, :with_initialize_with).name.should == 'trait initialize_with'
+  end
+end