Abstract: An anti-theft, portable clamp-on storage container for mounting in the load bed of a pickup truck comprises relatively movable top and bottom container sections which close to form an enclosure for goods. A screw clamp having an inverted U-shaped fixed jaw and a screw actuated movable jaw cooperable therewith is mounted with the inverted U-shaped fixed jaw supported exteriorly of the container bottom section and with the screw actuator for the movable jaw extending inside of the container. The fixed jaw is positioned to slide down over one of the side or end panels of the pickup truck load bed when the container is lowered into the floor of the load bed from above. A handle for turning the screw actuator is provided on the end of the screw actuator which is inside of the container so that the screw actuator can only be turned when the container is open.