An improved wheelbarrow includes a pair of legs that are each configured as four-bar linkages and are collapsible. Each of the legs includes an advantageously simple lock for releasably locking the leg in extended and retracted positions. The wheelbarrow includes a frame assembly, a wheel, a tray, and a pair of handles. The frame assembly can be assembled by the manufacturer, and the wheelbarrow can then be provided as a kit in accordance with the present invention that can be assembled by the retailer or the consumer by simply attaching the wheel, the tray, and the handles to the frame assembly. A support block is disclosed which facilitates assembly and strengthens the legs.