Abstract: A resilient foundation assembly for furniture expecially a box spring for supporting a mattress. A frame means which defines a generally planar foundation area, a grid means overlaying and spaced in a plane above and generally parallel to the foundation area plane and a plurality of spring units resiliently connected between the frame means and grid means. The spring units are formed of a single length of wire and comprise two end segments and a plurality of dual counter reaction modular coil springs contiguous therebetween. Each dual counter reaction spring comprises two leg sections extending downwardly from the grid plane toward the planar foundation area formed by the frame means, the two leg sections are joined by a bridging segment of wire lying in the grid plane. Each leg section is formed by linear segments of wire positioned in predetermined angular relationships and joined by a coil section of wire.