Abstract: At approximately 9:00 a.m. on September 21, 2007, Employee #1, a window installer, was working at a residential construction site in San Marcos, CA, where more than 100 two-story wood frames homes were under construction. He was using scaffolding that had already been erected around the exterior of the building to install windows on approximately ten homes. Employee #1 climbed out onto the scaffold from an opening in the second floor. The scaffolding was not fully planked; it had one plank in the area where he was standing and two planks in other parts. A coworker was standing on a ladder located on the stairway landing inside the house and was handing a large 5 ft sq window thru the opening to Employee #1. He was pushing the window into place when the scaffolding plank moved away from the house. Employee #1 fell, head first, 15 ft through the opening between the scaffolding and the side of the house. He landed on the dirt surface and suffered a fractured left hand and arm, lacerations, and a back injury. Employee #1 was transported to Palomar Hospital, where he underwent surgery and treatment.