A device for mounting planar lighting sources having a light emitting surface on a substrate includes a frame provided with fixing formations for fixing the frame on the substrate with the planar lighting source sandwiched between the frame and the substrate. The frame has an opening to surround the light emitting surface of said lighting source and is provided with elastic formations to elastically urge the lighting source toward the substrate. The fixing formations include at least one resilient formation to resiliently urge the frame toward the substrate.