This study examines the combined effects of the passenger airbag and the seat belt on the occupant impact response. It was found that while an airbag is beneficial in reducing unbelted occupant injury, its restraint force is in general additive to that of the belts in a 30 MPH barrier impact and tends to increase belted occupant response numbers. A number of possible design strategies were discussed and the inherent performance trade-offs among various impact conditions were illustrated. Concepts for two types of Adaptive Restraint System (ARS) are discussed which might achieve even greater levels of occupant protection for both belted and unbelted occupants. For a belted occupant, these ARS designs have embedded logic to determine when and how to use an airbag and/or a belt under various impact conditions. These ARS designs try to utilize the combined strengths of the airbag and the seat belt systems. Possible design strategies for these systems were also discussed.