Abstract: A tent enclosure for a pickup truck cargo box includes a pair of support tracks mounted to the side rails of the cargo box, a number of flexible support rods connected to the support tracks, and a fabric siding spanning the support rods and connected to the support tracks. The flexible support rods can be made up of multiple sections linked together, and, being longer than the width of the cargo box, describe an arch when connected to the support tracks. The forwardmost support rod can be secured to the truck cab. The fabric siding includes a U-channel edge for engaging the support track on each side of the cargo box, and is stretched over the support rods. The tent enclosure includes a door assembly for the end of the cargo box, which may be formed of fabric and integral with the fabric siding.