A generalized analytical model of an airbag inflation system has been developed and integrated into the CAL3D occupant dynamics simulation program. The new model allows for tabular input of mass flow rate and gas temperature to represent the inflator, and it accounts for airbag material stretch and airbag gas leakage. With this new model, the CAL3D program can be applied to evaluate the occupant protection performance of the majority of airbag inflation systems of practical interest. A separate gas dynamics analysis is also developed for generating the mass flow rate and gas temperature data for representing a pyrotechnic inflator, either when a tank test of the actual inflator is available or when a particular inflation characteristic is desired. Validation of the gas dynamics analysis and the new CAL3D airbag inflation model is demonstrated by application to a driver-side airbag system, for which a comparison is presented of the simulation predictions with the results of an actual barrier test.