Abstract: On June 23, 2009, Employee #1, a carpenter, the owner and a coworker were removing old skylights and installing new ones on a one-story house. They began the removal process by building a 2 ft by 6 ft wood curb frame, which would be placed around the old skylight opening. The wood curb was then transported onto the roof. They removed one old dome skylight, out of six, and attached the curb with screws. After installing the new skylight, they reattached the shingles around the skylight. They took a break following the work, and then returned to the roof. They removed additional roofing material (shingles and felt paper) from two skylights, and removed the old dome skylights, which left two openings, one 2.5 ft by 7.5 ft, and the other was 2.5 ft by 5.75 ft. The two hole openings were about 3.5 ft apart and staggered from each other. A coworker was located toward the top edge of one hole and Employee #1 was located on the other side toward the bottom edge, and was between the two holes. They had started replacing felt paper around and between the holes. Employee #1 stated that he had been kneeling on the roof, while doing the work and his knees felt uncomfortable and hot. He indicates that he stood up to relieve the pressure on his knees, when he stepped into the 2.5 ft by 7.5 ft opening and fell 11 ft to the floor of the house. He landed on a brick tile floor. His fall resulted in a fractured pelvis and four fractured transverse vertebrae, a laceration on his head and a lacerated spleen. Employee #1 stated that he was unconscious for a few minutes. Emergency medical personnel were summoned. They arrived and transported him to a location where he was airlifted to UCLA Medical Center. He underwent medical treatment and was hospitalized for eight days.