Abstract: Apparatus for mounting display devices on retail store modular shelving of the type that has hollow steel upright supporting posts each having a line of spaced longitudinal slots; with posts of laterally adjacent modules abutting one another or with adjacent modules hung on a single post. The mounting apparatus has a pair of fittings which engage vertically spaced post slots, a bracket which has an upright mounting arm is fastened to the fittings by two screws and has a display device supporting arm at right angles to the mounting arm, and a leveling screw goes through a threaded hole near the bottom of the mounting arm so as to bear against the post for leveling the bracket and fixing it firmly relative to the post. The fittings are constructed so two of them may be placed in coplanar slots of abutting posts in order to mount abutting display devices on laterally adjacent modules.