Abstract: At approximately 10:00 a.m. on August 24, 1995, Employee #1, a trained and experienced worker, was cleaning a roof area of debris, including plywood sheeting and material, as directed by the framing foreman. Earlier that morning, the framing foreman had inspected the roof to ensure that all of the roof openings and air conditioning penetrations (approximately 30 in. by 36 in.) were covered and secured; several were found uncovered. The previous day, he had removed and resecured the covers for the air conditioning foreman, who was inspecting the air conditioning openings. The framing foreman had left between 1:00 p.m. and 1:30 p.m. to go to another site. The air conditioning foreman continued his inspection but did not replace all the covers he removed. On the morning of the accident, the framing foreman sent a carpenter up to recover and secure two uncovered openings (only AC-3 and AC-4 were observed). Employee #1 was on the roof moving the last sheet from a stack of plywood, when he stepped back and fell 10 to 11 ft through an unmarked and unsecured opening, AC-6, that resulted from movement of the unmarked and unsecured plywood sheets. He landed on a concrete floor. Employee #1 was transported to Kaweah Delta Hospital, treated for a fractured tailbone, observed, and released.