a hard cover for the open bed of a pickup truck is thermoformed from two sheets of heat deformable plastic material . the top sheet has a slightly crowned surface and four depending walls defining a perimeter lip corresponding to the top ledge of a pickup truck bed . the bottom sheet reinforces the top sheet and is itself slightly crowned and includes four walls . the bottom sheet includes prop support members which depend below the margin defined by the perimeter lip of the hard cover . the perimeter lip of the hard cover may be adapted to reside within a range of similarity sized pickup truck bed rail margins , so that one hard cover can be utilized on several truck models . the hard cover may also be associated with a molded platform that overlays and closely conforms to the bed rails of a truck bed to provide a protective truck bed cover assembly . the molded platform is provided with a channel to receive the lip of the hard cover to provide a seal . the hard cover is releasibly attached to the molded platform , and the molded platform itself is adapted for direct installation to the truck bed . the molded platform is an intermediate interface between the hard cover and the truck bed . the molded platform protects the truck bed rail against damage when the present hard cover is supported upn the truck bed .