Abstract: A convertible mattress including a foundation unit, a support unit and a comfort unit. The foundation unit includes several spring elements that provide flexible support for an overlying grid which defines the foundation surface. The foundation unit may be supported by a bed frame which may further include side boards, a head board and foot board. The comfort unit, or innerspring, is located atop the foundation unit and contains several interconnected spring coils or a foam core structure. The top and bottom surface of the comfort unit contain minimal covering to provide a smooth surface over the ends of the coils of the innerspring. The comfort unit is located atop the support unit and has a generally horizontal top and bottom and generally vertical sides extending between the top and bottom that defines a central space containing support and cushioning components such as foam.