Abstract: This invention is directed to an improved mattress and mattress core which provide increased firmness along the edges and transverse center section. The mattress includes a mattress core, padding over at least one side of the core, and an upholstered covering encasing the mattress core and padding. The improved mattress core has a rectangular coil spring assembly and a pair of rectangular outer border rods surrounding the assembly in the top and bottom planes of the mattress core. The improved core also includes means for increasing the firmness of the edges and the transverse center portion of the mattress, including a pair of rectangular inner border rods spaced inwardly from an outer border rod in at least one of the top and bottom planes of the rectangular coil spring assembly. A preferred embodiment has one pair of inner border rods in the top plane and a second pair in the bottom plane substantially underlying the first pair.