Abstract: A lighting fixture adapted to be mounted on a ceiling by attachment to an outlet box in the ceiling. The fixture comprises a crossbar attached to the bottom of the outlet box in a position extending horizontally across the bottom of the box and of such length as to extend at both ends beyond the box. The crossbar has downwardly extending legs and generally horizontally extending feet at the lower ends of the legs. The fixture further has a plate below the crossbar with thermally insulated spacer means between the plate and the crossbar. Screws secure the plate to the crossbar with the spacer means between the plate and the crossbar. The screws extend up through holes in the plate and are threaded into holes in the feet. A light source and diffuser for the light source are secured on the bottom of the plate and to the rim of the plate, respectively.