Abstract: An improved skylight system comprises a unitary light transmitting skylight lens having a main lens body, an outwardly projecting horizontal support flange, a surrounding downwardly and outwardly extending skirt panel, and a horizontal lower attachment lip extending from the skirt panel. The attachment lip is held in a channel formed by an upper hold-down flange and a cooperating lower flange of a mounting frame. The lens is fitted over a roof curb and attached thereto by driving fasteners through a vertical attachment collar that depends from the inner edge of the lower flange of the mounting frame into the curb.