Abstract: An illuminated sign assembly has a cabinet of somewhat resilient sheet material with a self-hinging sign frame on at least one side which snap fits into the cabinet without use of a conventional hinge. An assembly may be provided for security and tensioning the vinyl sheet of a sign face into the frame. The snap action is provided by interaction between a channel defined by a system of resilient flanges formed by a portion of the cabinet to which the frame is hinged, and an abutment on a rearwardly extending flange on a hinged side of the frame.