A universal shelf bracket composed of three basic interlocking components held together and adjusted by a screw and rectangular nut. The bracket engages a pair of vertically aligned slots in a vertical wall and can be adjusted to fit a variety of slot spacings and depths. The bracket is constructed so that its tabs are both flush with the same outer wall while still allowing the bracket to fit squarely in the slots. Left and right brackets can be constructed so that two brackets can be engaged to one common pair of vertically aligned slots.