diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 78082665a48e..31e1c22f0d0e 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,3 +1,5 @@
+* Add ActiveRecord::Base.sti_name that checks ActiveRecord::Base#store_full_sti_class? and returns either the full or demodulized name. [rick]
+
 * Add first/last methods to associations/named_scope. Resolved #226. [Ryan Bates]
 
 *2.1.0 RC1 (May 11th, 2008)*
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index ebcf462f2e63..52ced36d1692 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -237,7 +237,7 @@ def build_through_conditions
         end
         
         def build_sti_condition
-          "#{@reflection.through_reflection.quoted_table_name}.#{@reflection.through_reflection.klass.inheritance_column} = #{@reflection.klass.quote_value(@reflection.through_reflection.klass.name.demodulize)}"
+          "#{@reflection.through_reflection.quoted_table_name}.#{@reflection.through_reflection.klass.inheritance_column} = #{@reflection.klass.quote_value(@reflection.through_reflection.klass.sti_name)}"
         end
 
         alias_method :sql_conditions, :conditions
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index d2d9bda6ba05..92a24ecc5f5c 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -1293,6 +1293,10 @@ def respond_to?(method_id, include_private = false)
         super
       end
 
+      def sti_name
+        store_full_sti_class ? name : name.demodulize
+      end
+
       private
         def find_initial(options)
           options.update(:limit => 1)
@@ -1452,7 +1456,11 @@ def instantiate(record)
         # Nest the type name in the same module as this class.
         # Bar is "MyApp::Business::Bar" relative to MyApp::Business::Foo
         def type_name_with_module(type_name)
-          (/^::/ =~ type_name) ? type_name : "#{parent.name}::#{type_name}"
+          if store_full_sti_class
+            type_name
+          else
+            (/^::/ =~ type_name) ? type_name : "#{parent.name}::#{type_name}"
+          end
         end
 
         def construct_finder_sql(options)
@@ -1571,8 +1579,8 @@ def add_conditions!(sql, conditions, scope = :auto)
 
         def type_condition
           quoted_inheritance_column = connection.quote_column_name(inheritance_column)
-          type_condition = subclasses.inject("#{quoted_table_name}.#{quoted_inheritance_column} = '#{store_full_sti_class ? name : name.demodulize}' ") do |condition, subclass|
-            condition << "OR #{quoted_table_name}.#{quoted_inheritance_column} = '#{store_full_sti_class ? subclass.name : subclass.name.demodulize}' "
+          type_condition = subclasses.inject("#{quoted_table_name}.#{quoted_inheritance_column} = '#{sti_name}' ") do |condition, subclass|
+            condition << "OR #{quoted_table_name}.#{quoted_inheritance_column} = '#{subclass.sti_name}' "
           end
 
           " (#{type_condition}) "
@@ -2508,7 +2516,7 @@ def create
       # Message class in that example.
       def ensure_proper_type
         unless self.class.descends_from_active_record?
-          write_attribute(self.class.inheritance_column, store_full_sti_class ? self.class.name : self.class.name.demodulize)
+          write_attribute(self.class.inheritance_column, self.class.sti_name)
         end
       end
 
diff --git a/activerecord/test/cases/inheritance_test.rb b/activerecord/test/cases/inheritance_test.rb
index 27394924a15a..f09b617e6d3b 100755
--- a/activerecord/test/cases/inheritance_test.rb
+++ b/activerecord/test/cases/inheritance_test.rb
@@ -5,7 +5,23 @@
 
 class InheritanceTest < ActiveRecord::TestCase
   fixtures :companies, :projects, :subscribers, :accounts
-  
+
+  def test_class_with_store_full_sti_class_returns_full_name
+    old = ActiveRecord::Base.store_full_sti_class
+    ActiveRecord::Base.store_full_sti_class = true
+    assert_equal 'Namespaced::Company', Namespaced::Company.sti_name
+  ensure
+    ActiveRecord::Base.store_full_sti_class = old
+  end
+
+  def test_class_without_store_full_sti_class_returns_demodulized_name
+    old = ActiveRecord::Base.store_full_sti_class
+    ActiveRecord::Base.store_full_sti_class = false
+    assert_equal 'Company', Namespaced::Company.sti_name
+  ensure
+    ActiveRecord::Base.store_full_sti_class = old
+  end
+
   def test_should_store_demodulized_class_name_with_store_full_sti_class_option_disabled
     old = ActiveRecord::Base.store_full_sti_class
     ActiveRecord::Base.store_full_sti_class = false