Controller/view changes for editing nested forms?

I've successfully set up a nested form from the controller:

  def new
    @user = User.new
    @user.build_contact.build_address

    respond_to do |format|
      format.html # new.html.erb
      format.xml { render :xml => @user }
    end
  end

and have edited the new.html.erb file to suit, with fields_for in the
appropriate places. The form successfully creates contact and address records
when saved, and I can see linked objects when I simply create them at the
console. However, selecting edit from the index brings up the edit.html.erb
view (practically identical to new.html.erb) but isn't populating the nested
fields--only the ones from User get populated, but Contact and Address
remain blank even though the records exist.

Do I need to change something in the edit() to populate the fields for
the nested objects? I currently have:

  def edit
    @user = User.find(params[:id])
  end

Or do I need to change the view somehow to access the nested objects
differently when I edit than I do when I create?