Abstract: On June 26, 2007, Employee #1, age 19 years, and four coworkers were replacing an approximately 80-foot wide by 260-foot long flat roof. The job involved cutting off the entire outer sheathing and removing all 17 skylights and various exhaust hoods. Apparently, the eastern 40 feet and northern 12 feet of the entire building length had been completely reroofed. However, the new skylights had not been placed yet. The three skylight openings at the east end were covered with 0.875-inch particle board. Employee #1 and a coworker removed the 4-foot by 8-foot sheets of particle board, and Employee #1 apparently stepped into one of the skylight openings and fell approximately 19 feet to the ground. Employee #1 was killed. The skylight openings had a 7.5-inch-tall lip, which Employee #1 had to have stepped over. The accident occurred during the first hour of Employee #1's first day on the job. Subsequent investigation found fall protection deficiencies around the skylights and along the roof perimeter. In addition, the employer had not adequately implemented a flagging system.