Abstract: A modular bed foundation to support the weight of a mattress and eliminate the need for a box spring. The bed foundation has a pair of end sections, a pair of side sections, and a plurality of horizontally extending mattress support slats detachably connected to the pair of side sections without the use of fasteners. First and second sets of legs are detachably connected to respective leg receivers at the pair of side sections without the use of fasteners. An improved corner assembly enables each of the pair of end sections to be detachably connected to an adjacent one of the pair of side sections without the use of fasteners. The improved corner assembly includes a corner post having a pair of corner inserts projecting therefrom to be slidably and removably received within hollow rails of one of the pair of end sections.