diff --git a/lib/mongoid/associations.rb b/lib/mongoid/associations.rb
index 2278ddd79d..80baa88ccc 100644
--- a/lib/mongoid/associations.rb
+++ b/lib/mongoid/associations.rb
@@ -227,7 +227,7 @@ def add_association(type, options)
       def add_builder(type, options)
         name = options.name.to_s
         define_method("build_#{name}") do |attrs|
-          reset(name) { type.new(self, attrs, options) }
+          reset(name) { type.new(self, attrs.stringify_keys, options) }
         end
       end
 
diff --git a/lib/mongoid/associations/belongs_to.rb b/lib/mongoid/associations/belongs_to.rb
index ce273bba30..f5fbdbdc45 100644
--- a/lib/mongoid/associations/belongs_to.rb
+++ b/lib/mongoid/associations/belongs_to.rb
@@ -5,7 +5,7 @@ class BelongsTo #:nodoc:
       include Proxy
 
       # Creates the new association by setting the internal
-      # document as the passed in Document. This should be the
+      # target as the passed in Document. This should be the
       # parent.
       #
       # All method calls on this object will then be delegated
@@ -13,7 +13,7 @@ class BelongsTo #:nodoc:
       #
       # Options:
       #
-      # document: The parent +Document+
+      # target: The parent +Document+
       # options: The association options
       def initialize(target, options)
         @target, @options = target, options
@@ -26,11 +26,6 @@ def find(id)
         @target
       end
 
-      # Delegate all missing methods over to the parent +Document+.
-      def method_missing(name, *args, &block)
-        @target.send(name, *args, &block)
-      end
-
       class << self
         # Creates the new association by setting the internal
         # document as the passed in Document. This should be the
@@ -53,6 +48,10 @@ def macro
         # Perform an update of the relationship of the parent and child. This
         # is initialized by setting a parent object as the association on the
         # +Document+. Will properly set a has_one or a has_many.
+        #
+        # Returns:
+        #
+        # A new +BelongsTo+ association proxy.
         def update(target, child, options)
           child.parentize(target, options.inverse_of)
           child.notify
diff --git a/lib/mongoid/associations/has_one.rb b/lib/mongoid/associations/has_one.rb
index 2e5de32f96..86834d9829 100644
--- a/lib/mongoid/associations/has_one.rb
+++ b/lib/mongoid/associations/has_one.rb
@@ -4,7 +4,10 @@ module Associations #:nodoc:
     class HasOne #:nodoc:
       include Proxy
 
-      attr_reader :association_name, :document, :parent, :options
+      # Build a new object for the association.
+      def build(attrs = {}, type = nil)
+        @target = attrs.assimilate(@parent, @options, type); self
+      end
 
       # Creates the new association by finding the attributes in
       # the parent document with its name, and instantiating a
@@ -16,43 +19,31 @@ class HasOne #:nodoc:
       # Options:
       #
       # document: The parent +Document+
-      # attributes: The attributes of the decorated object.
+      # attributes: The attributes of the target object.
       # options: The association options.
-      def initialize(document, attributes, options)
-        @parent, @options, @association_name = document, options, options.name
-        attrs = attributes.stringify_keys
-        klass = attrs["_type"] ? attrs["_type"].constantize : nil
-        @document = attrs.assimilate(@parent, @options, klass)
-      end
-
-      # Delegate all missing methods over to the +Document+.
-      def method_missing(name, *args, &block)
-        @document.send(name, *args, &block)
+      #
+      # Returns:
+      #
+      # A new +HashOne+ association proxy.
+      def initialize(document, attrs, options)
+        @parent, @options  = document, options
+        @target = attrs.assimilate(@parent, @options, attrs.klass)
       end
 
       # Used for setting the association via a nested attributes setter on the
-      # parent +Document+.
+      # parent +Document+. Called when using accepts_nested_attributes_for.
+      #
+      # Options:
+      #
+      # attributes: The attributes for the new association
+      #
+      # Returns:
+      #
+      # A new target document.
       def nested_build(attributes)
         build(attributes)
       end
 
-      # This will get deprecated
-      def to_a
-        [@document]
-      end
-
-      # Need to override here for when the underlying document is nil.
-      def valid?
-        @document.valid?
-      end
-
-      protected
-      # Build a new object for the association.
-      def build(attrs = {}, type = nil)
-        @document = attrs.assimilate(@parent, @options, type)
-        self
-      end
-
       class << self
         # Preferred method of instantiating a new +HasOne+, since nil values
         # will be handled properly.
@@ -84,8 +75,13 @@ def macro
         # Example:
         #
         # <tt>HasOne.update({:first_name => "Hank"}, person, options)</tt>
+        #
+        # Returns:
+        #
+        # A new +HasOne+ association proxy.
         def update(child, parent, options)
           child.assimilate(parent, options)
+          instantiate(parent, options)
         end
       end
 
diff --git a/lib/mongoid/associations/proxy.rb b/lib/mongoid/associations/proxy.rb
index ffddd92d64..f93f4f9916 100644
--- a/lib/mongoid/associations/proxy.rb
+++ b/lib/mongoid/associations/proxy.rb
@@ -14,6 +14,12 @@ module InstanceMethods #:nodoc:
         attr_reader \
           :options,
           :target
+
+        # Default behavior of method missing should be to delegate all calls
+        # to the target of the proxy. This can be overridden in special cases.
+        def method_missing(name, *args, &block)
+          @target.send(name, *args, &block)
+        end
       end
     end
   end
diff --git a/lib/mongoid/extensions/hash/accessors.rb b/lib/mongoid/extensions/hash/accessors.rb
index 92cfd4ee09..fdf61e7beb 100644
--- a/lib/mongoid/extensions/hash/accessors.rb
+++ b/lib/mongoid/extensions/hash/accessors.rb
@@ -26,6 +26,12 @@ def insert(key, attrs)
             self[key] = key.singular? ? attrs : [attrs]
           end
         end
+
+        # If a _type key exists in the hash, return the class for the value.
+        def klass
+          class_name = self["_type"]
+          class_name ? class_name.constantize : nil
+        end
       end
     end
   end
diff --git a/spec/unit/mongoid/associations/has_one_spec.rb b/spec/unit/mongoid/associations/has_one_spec.rb
index 5674e301e6..d087e6ba62 100644
--- a/spec/unit/mongoid/associations/has_one_spec.rb
+++ b/spec/unit/mongoid/associations/has_one_spec.rb
@@ -178,7 +178,7 @@
       before do
         @name = Name.new(:first_name => "Donald")
         @person = Person.new(:title => "Sir")
-        Mongoid::Associations::HasOne.update(
+        @association = Mongoid::Associations::HasOne.update(
           @name,
           @person,
           Mongoid::Associations::Options.new(:name => :name)
@@ -194,6 +194,10 @@
           { "_id" => "donald", "first_name" => "Donald", "_type" => "Name" }
       end
 
+      it "returns the proxy" do
+        @association.target.should == @name
+      end
+
     end
 
     context "when setting the object to nil" do
@@ -216,6 +220,22 @@
 
   end
 
+  describe "#to_a" do
+
+    before do
+      @association = Mongoid::Associations::HasOne.new(
+        @document,
+        @attributes["mixed_drink"],
+        Mongoid::Associations::Options.new(:name => :mixed_drink)
+      )
+    end
+
+    it "returns the target in a new array" do
+      @association.to_a.first.should be_a_kind_of(MixedDrink)
+    end
+
+  end
+
   describe "#valid?" do
 
     context "when the document is not nil" do
diff --git a/spec/unit/mongoid/extensions/hash/accessors_spec.rb b/spec/unit/mongoid/extensions/hash/accessors_spec.rb
index 305372ed12..dc4e4fa6d5 100644
--- a/spec/unit/mongoid/extensions/hash/accessors_spec.rb
+++ b/spec/unit/mongoid/extensions/hash/accessors_spec.rb
@@ -21,6 +21,26 @@
     }
   end
 
+  describe "#klass" do
+
+    context "when _type exists" do
+
+      it "returns the class" do
+        { "_type" => "Person" }.klass.should == Person
+      end
+
+    end
+
+    context "when _type does not exist" do
+
+      it "returns nil" do
+        {}.klass.should be_nil
+      end
+
+    end
+
+  end
+
   describe "#remove" do
 
     context "when removing from an array" do