Abstract: An adjustable signal light which is attachable to the rear window of a vehicle. The signal light has a bracket with a frame that may be secured to the inside surface of the vehicle rear window by adhesive means, and a pair of spaced side fins which extend from opposed sides of the frame. A lamp housing is rotatably mounted between the bracket side fins and defines a lamp chamber open generally toward the frame opening at a desired angle thereto. A lamp is mounted within the chamber and electrical means connect the lamp to the electrical system of the vehicle. A lens is secured to the housing to enclose the lamp in the lamp housing and refract light from the lamp through the frame opening. A removeable cover is engaged on the bracket to enclose the lamp housing and secure the bracket side fins in locking engagement with the lamp housing to prevent rotation of the lamp housing during use.