A modular shelving system includes a wall panel with slots and shelf brackets with tabs which attach to the wall panel slots. The tabs have upwardly sloping surfaces which engage sloped surfaces on the back side of the slots. These mating surfaces better retain the tabs into the slots and provide a higher degree of strength in the tab and slot joint. This allows the shelving system to be made with smaller tabs and thinner material than previously possible; providing a more secure and visually appealing shelving system.