Abstract: A ladder for a truck box comprising a bracket assembly adapted to be placed over the upper edge of the truck box having a ladder assembly pivotally secured at its upper end to the bracket assembly so that the ladder assembly will remain vertically disposed regardless of the inclination of the truck box. The ladder assembly comprises an outer frame assembly pivotally connected to an inner frame assembly so that the outer frame assembly may be pivotally moved from an inoperative position closely adjacent the inner frame to an operative position wherein the outer frame is spaced outwardly of the inner frame. Steps pivotally interconnect the inner and outer frames.