Abstract: Employee #1 and a coworker, both masons, were installing a 400 lb, 41 in. long by 12 in. wide by 10 in. high coping stone on an approximately 20 ft high concrete pier that had a brick veneer. A forklift was used to lift the stone to the work level, and the two masons then slid the stone onto the pier. As they were setting and leveling the stone, which was offset approximately 5 in. from the brick veneer beneath it, the stone suddenly tilted and fell. It broke through the 2 ft wide by 10 ft long scaffold-rated board on which Employee #1 was standing, causing him to fall to the floor below. He sustained a fractured pelvis, knee, and wrist, as well as severe facial lacerations from falling face first onto the screw jack at the scaffold's base. The employer had previously installed extensive quantities of this type of stone in similar situations throughout the job site without mishap.