A window frame assembly for installation within a garage door having front and rear exposed surfaces and one or more window openings. The assembly includes front and rear window frame members of injection molded plastic which are installed within the door opening on the front and rear exposed surfaces. The window frame members have alignment elements to assist in assemble and have engagement elements located about their peripheries which snap together in mating fashion to mount the frame members within the window opening. The engagement elements are adjustable to accommodate garage door panels of varying thicknesses and window panes of varying thicknesses. The engagement elements are also disengageable with a hand tool to separate the frame members and remove the members from the window opening.