Abstract: A modular display system comprises a plurality of identical modules. Each module includes a vertical mounting surface, a pair of sidewalls, top surface and a bottom surface lying in planes which extend at right angles to the mounting surface. A pair of top rails lie above the top plane and form outward facing channels. A pair of bottom rails extend inward from respective sidewalls just above the bottom plane, each bottom rail engaging in a respective channel when two modules are assembled one above the other. The inner surfaces of at least one of the top rails and the bottom rails converge toward the top or bottom plane at an acute angle so that the inner surfaces of the top rails are received against the inner surfaces of the bottom rails in a press fit. The modules are latched in this position by a detent and shoulder arrangement.