Abstract: A unitary mattress assembly comprises a plurality of coil springs interarranged to define a single innerspring core having a generally rectangular shape in plan. The core has a first portion which is sized to accommodate a first sleeping person and comprises coil springs having a first preselected compressive strength. Adjacent to the first portion is a second core portion sized to accommodate another sleeping person and having coil springs of a different compressive strength than the springs of the first portion. By the foregoing construction, a mattress may be manufactured having a single innerspring core but having two regions of differing firmness to suit the particular preferences of two people.