A modular pallet system has two or more pallets, each of which has four legs and which is capable of standing on its own as an independent unit. The pallets are formed to dimensions which are a fraction of conventional pallet sizes, such that one pallet alone serves as a quarter of a standard dimensioned pallet, while two pallets combined serve as a half of a standard dimensioned pallet. Each pallet has tabs and slots on the perimeter edges, with the result that two or more of the small pallets can be assembled into a standard size pallet in an interference fit without tools. The pallets may be produced as single sheet thermoformed or twin sheet thermoformed parts, or could be injection molded or structural foam molded. An adapter may be attached in a snap fit beneath four joined pallets to facilitate interaction between the combined pallets and conventional racks and conveyors, and to facilitate stacking.