This paper discusses how to turn a 3-point inertia belt into a passive seat-belt system. The main objectives of the program were to prove that it would be possible to use existing seatbelt systems to cope with future requirements for occupant restraints and that therefore existing anchor points (or at least the existing systems) could be used. The aim was to use only existing techniques in order to reach a high reliability standard and to design a system that also could meet current homologation requirements. A prototype was developed with a combination of a 3-point seat belt with running loop with an inertia reel at the central lap belt, in combination with loops around the webbing of the seat belt running along cable-operated tracks. The prototype met all the objectives.