A pull-out step assembly for a cargo box vehicle is disclosed. The assembly provides one or two steps to access the cargo box of a pickup truck or similar vehicle. The pull-out step assembly can be deployed with the tail gate of the cargo box in a closed or open condition. The pull-out step assembly attaches to the vehicle frame and stores beneath the cargo box when not in use. Also disclosed is a protective box member that covers the step assembly when stored beneath the cargo box.