Abstract: A shelving system includes first and second support members extending in parallel vertical planes, and a pair of shelves mounted intermediate the support members. Each of the shelves has a longitudinal pivot axis perpendicular to the planes of the support members. Each shelf is continuously positionable at any angular orientation about its pivot axis. Each of the support members includes an upper and a lower stacking surface. Modular units may be stacked to form a larger shelving system wherein mating upper and lower stacking surfaces abut. To facilitate alignment when stacked, the stacking surfaces include first and second alignment portions, and upper and lower alignment cavities formed in each support member. To maintain alignment of the units, an alignment member is received in mutually facing alignment cavities in the assembled shelving system.