The report details how NHTSA produces these lives saved estimates for seat belts and frontal air bags. The methodology is described in detail, including the use of effectiveness ratings for seat belts and frontal air bags. Seat belt effectiveness ratings vary according to the seat belt type (i.e., 3-point belt versus 2-point lap belt), vehicle type, occupant seating position, and occupant age. Frontal air bag effectiveness ratings are consistent for all passenger vehicles. The interactions of the effectiveness of seat belts and the effectiveness of frontal air bags are discussed in this report.