Abstract: An alignment tool for establishing the proper location for boring a hole in a door to receive the cylinder of a lock so that the lock will be properly aligned with the strike in a lock of the type colloquially referred to as a "jimmy-proof" lock. The strike, which has two bolt-receiving protruding flanges, is installed in the proper place on the door jamb. The alignment tool is then mounted on the strike, the tool including an elongated bar dimensioned to fit between the strike flanges and having an opening which is to be aligned with the flange openings. A peg is inserted through the flange openings and the opening in the end of the bar so that the bar is pivotable about the central axis of the flange openings. A threaded bolt penetrates the other end of the bar and the bar is moved so that the end of the bolt contacts the door surface. The bolt is then rotated until the bar is parallel with the door surface.