Abstract: At about 3:30 p.m. on August 27, 1987, Employee #1 and a coworker, of O'Brien Associates, Inc., Annapolis, MD, were at Greenbriar Condominiums, Greenbelt, MD, working from a pump jack scaffold. They were standing on a 10 ft long by 19 in. wide scaffold platform that was about 29 ft from the ground. The space between the platform and the building wall was about 6 in. A 10 ft by 19 in. workbench had been installed on the scaffold about 3 ft above the work platform and was also used as a top guardrail. Neither a midrail nor a toe board had been installed on the scaffold. The north end of the platform was against the building wall and the other end was unguarded and open. The employees were working at about shoulder height, installing insulation material to the building wall. Employee #1, who was near the unguarded end of the scaffold, started moving toward the other end to get some materials. As he moved he lost his footing and fell between the work bench and the platform to the ground. He was hospitalized for his injuries. Employee #1 had experience working on a pump jack scaffold. Personal protective equipment--i.e., safety belt, lanyard, and lifeline--were not used.