diff --git a/lib/curator.rb b/lib/curator.rb
index b78019a..aaf5a3e 100644
--- a/lib/curator.rb
+++ b/lib/curator.rb
@@ -1,5 +1,6 @@
 require 'rubygems'
 
+require 'curator/mapper'
 require 'curator/migration'
 require 'curator/migrator'
 require 'curator/model'
diff --git a/lib/curator/mapper.rb b/lib/curator/mapper.rb
new file mode 100644
index 0000000..87ccd41
--- /dev/null
+++ b/lib/curator/mapper.rb
@@ -0,0 +1,27 @@
+module Curator
+  class Mapper
+    def initialize(field_name, options)
+      @field_name = field_name
+      @serialize_function = options[:serialize]
+      @deserialize_function = options[:deserialize]
+    end
+
+    def deserialize(attributes)
+      _map(attributes, @deserialize_function)
+    end
+
+    def serialize(attributes)
+      _map(attributes, @serialize_function)
+    end
+
+    def _map(attributes, mapping_function)
+      current_value = attributes[@field_name]
+      if current_value && mapping_function
+        mapped_value = mapping_function.call(current_value)
+        attributes.merge(@field_name => mapped_value)
+      else
+        attributes
+      end
+    end
+  end
+end
diff --git a/lib/curator/repository.rb b/lib/curator/repository.rb
index a78aaf7..d440f86 100644
--- a/lib/curator/repository.rb
+++ b/lib/curator/repository.rb
@@ -55,6 +55,14 @@ def klass
         name.to_s.gsub("Repository", "").constantize
       end
 
+      def map(field_name, options)
+        _mappers << Mapper.new(field_name, options)
+      end
+
+      def _mappers
+        @mappers ||= []
+      end
+
       def migrator
         @migrator ||= Curator::Migrator.new(collection_name)
       end
@@ -82,7 +90,8 @@ def save_without_timestamps(object)
       end
 
       def serialize(object)
-        object.instance_values
+        attributes = object.instance_values.with_indifferent_access
+        _mappers.inject(attributes) { |attrs, mapper| mapper.serialize(attrs) }
       end
 
       def _build_finder_methods(field_name)
@@ -106,7 +115,8 @@ def _find_by_index(collection_name, field_name, value)
       end
 
       def deserialize(attributes)
-        klass.new(attributes)
+        mapped_attributes = _mappers.inject(attributes) { |attrs, mapper| mapper.deserialize(attrs) }
+        klass.new(mapped_attributes)
       end
 
       def _deserialize(id, data)
diff --git a/spec/curator/mapper_spec.rb b/spec/curator/mapper_spec.rb
new file mode 100644
index 0000000..7c7c4f7
--- /dev/null
+++ b/spec/curator/mapper_spec.rb
@@ -0,0 +1,37 @@
+require 'spec_helper'
+
+describe Curator::Mapper do
+  describe "serialize" do
+    it "serializes a field" do
+      mapper = Curator::Mapper.new(:foo, :serialize => lambda { |v| v + 1 })
+      mapper.serialize(:foo => 1).should == {:foo => 2}
+    end
+
+    it "ignores other fields" do
+      mapper = Curator::Mapper.new(:foo, :serialize => lambda { |v| v + 1 })
+      mapper.serialize(:bar => 1).should == {:bar => 1}
+    end
+
+    it "leaves fields alone if there is no option" do
+      mapper = Curator::Mapper.new(:foo, {})
+      mapper.serialize(:foo => 1).should == {:foo => 1}
+    end
+  end
+
+  describe "deserialize" do
+    it "deserializes a field" do
+      mapper = Curator::Mapper.new(:foo, :deserialize => lambda { |v| v + 1 })
+      mapper.deserialize(:foo => 1).should == {:foo => 2}
+    end
+
+    it "ignores other fields" do
+      mapper = Curator::Mapper.new(:foo, :deserialize => lambda { |v| v + 1 })
+      mapper.deserialize(:bar => 1).should == {:bar => 1}
+    end
+
+    it "leaves fields alone if there is no option" do
+      mapper = Curator::Mapper.new(:foo, {})
+      mapper.deserialize(:foo => 1).should == {:foo => 1}
+    end
+  end
+end
diff --git a/spec/curator/repository_spec.rb b/spec/curator/repository_spec.rb
index ace4922..8c4701e 100644
--- a/spec/curator/repository_spec.rb
+++ b/spec/curator/repository_spec.rb
@@ -306,4 +306,42 @@ def migrate(hash)
       repository.save_without_timestamps(model).should == model
     end
   end
+
+  describe "mapping" do
+    it "runs serialize and deserialize" do
+      repository = test_repository do
+        map :some_field, :serialize => lambda { |i| (i + 1).to_s }, :deserialize => lambda { |str| "5#{str}".to_i }
+      end
+
+      model = TestModel.new(:some_field => 3)
+      repository.save(model)
+
+      found_model = repository.find_by_id(model.id)
+      found_model.some_field.should == 54
+    end
+
+    it "does not change value when no serialize is specified" do
+      repository = test_repository do
+        map :some_field, :deserialize => lambda { |str| Date.parse(str) }
+      end
+
+      model = TestModel.new(:some_field => Date.today)
+      repository.save(model)
+
+      found_model = repository.find_by_id(model.id)
+      found_model.some_field.should == Date.today
+    end
+
+    it "leaves value as is when no deserialize is specified" do
+      repository = test_repository do
+        map :some_field, :serialize => lambda { |date| date.year }
+      end
+
+      model = TestModel.new(:some_field => Date.today)
+      repository.save(model)
+
+      found_model = repository.find_by_id(model.id)
+      found_model.some_field.should == Date.today.year
+    end
+  end
 end