Abstract: An enclosure is described for the box of a pick-up truck. The box of a pickup truck is defined by a front wall, side walls and a rear gate the flat upper surfaces of the box forming a rectangle. The enclosure has a front wall, side walls and a rear gate which has a lower flange surface substantially congruent with the uppermost, outermost edge of the box, and mountable atop same. This defines a space enclosed by the box and an enclosure. The enclosure of the present invention is hinged internally within the defined space and is characterized in that between the other side wall of an enclosure of the invention and the corresponding side wall of a box is provided a pair of lifting arms to assist in the lifting, and closing, of said enclosure and a pair of latches to keep the enclosure in the lowermost closed position and is further defined by a weatherproof seal.