Index: lib/data_mapper/property.rb
===================================================================
--- lib/data_mapper/property.rb	(revision 720)
+++ lib/data_mapper/property.rb	(working copy)
@@ -143,7 +143,7 @@
     PROPERTY_OPTIONS = [
       :public, :protected, :private, :accessor, :reader, :writer,
       :lazy, :default, :nullable, :key, :serial, :column, :size, :length,
-      :format, :index, :check, :ordinal, :auto_validation
+      :format, :index, :check, :ordinal, :auto_validation, :references
     ]
     
     VISIBILITY_OPTIONS = [:public, :protected, :private]
Index: lib/data_mapper/adapters/sql/mappings/column.rb
===================================================================
--- lib/data_mapper/adapters/sql/mappings/column.rb	(revision 720)
+++ lib/data_mapper/adapters/sql/mappings/column.rb	(working copy)
@@ -6,7 +6,7 @@
         # TODO: There are of course many more options to add here.
         # Ordinal, Length/Size, Nullability are just a few.
         class Column
-          attr_reader :type, :name, :ordinal, :size, :default, :check
+          attr_reader :type, :name, :ordinal, :size, :default, :check, :references
           attr_writer :lazy, :index, :unique
           attr_accessor :table, :options
           
@@ -28,6 +28,7 @@
             @unique = if @options[:index] == :unique then @options.delete(:index); true else false end
             @index = @options[:index]
             @check = @options[:check] # only for postgresql
+            @references = @options[:references] #only for postgresql
             
             @size = if @options.has_key?(:size)
               @options[:size]
Index: lib/data_mapper/adapters/postgresql_adapter.rb
===================================================================
--- lib/data_mapper/adapters/postgresql_adapter.rb	(revision 720)
+++ lib/data_mapper/adapters/postgresql_adapter.rb	(working copy)
@@ -58,8 +58,19 @@
       
       TYPES.merge!({
         :integer => 'integer'.freeze,
-        :datetime => 'timestamp with time zone'.freeze
+        :datetime => 'timestamp with time zone'.freeze,
       })
+      
+      FOREIGN_KEY_MATCHES = {
+        :full => "FULL".freeze,
+        :partial => "PARTIAL".freeze,
+        :simple => "SIMPLE".freeze
+      }
+      
+      FOREIGN_KEY_ACTIONS = {
+        :restrict => "RESTRICT".freeze,
+        :cascade => "CASCADE".freeze,
+        :set_null => "SET NULL".freeze }
         
       module Mappings
         class Table
@@ -154,6 +165,18 @@
           	"CHECK (" << check << ")"
           end
           
+          def references_declaration
+            out = ""
+            
+            out << "REFERENCES " << references[:reftable]
+            out << "(" << references[:refcolumn] << ")" if references.has_key?(:refcolumn)
+            out << " MATCH " << FOREIGN_KEY_MATCHES[references[:match]] if references.has_key?(:match)
+            out << " ON DELETE " << FOREIGN_KEY_ACTIONS[references[:on_delete]]if references.has_key?(:on_delete)
+            out << " ON UPDATE " << FOREIGN_KEY_ACTIONS[references[:on_update]] if references.has_key?(:on_update)
+            
+            out
+          end
+          
           def to_alter_sql
             "ALTER TABLE " <<  table.to_sql << " ALTER COLUMN " << to_alter_form
           end
@@ -234,12 +257,17 @@
                 if check && !check_declaration.blank?
                   @to_long_form << " #{check_declaration}"
                 end
+                
+                if references && !references_declaration.blank?
+                  @to_long_form << " #{references_declaration}"
+                end
               end
                       
               @to_long_form
             end
           end
           
+          # size is still required, as length in postgres behaves slightly differently
           def size
             nil
           end