A flexible cargo bed tie-down system allows the user to easily change, adjust, customize, and adapt his or her vehicle to specific needs at any given moment, and interfaces with the rest of the vehicle in an optimum manner from a functional, structural, and aesthetic standpoint. One embodiment of the invention provides a vehicle having a side wall construction enclosing a cargo bed at a side of the cargo bed. The side wall construction includes an outer portion which runs generally vertically at an outer portion of the vehicle, and a top portion which runs generally horizontally from the outer portion toward a longitudinal center of the vehicle. A tie-down rail is mounted adjacent to the top portion such that a part of the top portion overhangs at least a portion of the tie-down rail. The tie-down rail is configured to accept a tie-down fitting and includes a slotted opening generally aligned with an interior edge of the top portion.