Occupant protection in side impacts have been actively pursued in recent years. Roughly about one third of all automobile crashes involve side collisions. A majority of fatalities in side collisions are due to injuries in the thorax, head and neck region of the occupant. Modeling and simulation are becoming increasingly popular to help develop restraint systems and enhance the value of the design. The use of analytical tools along with laboratory testing can help improve the effectiveness and the speed of developing and implementing a restraint system to help maximize occupant protection.The development of a detailed and state-of-the-art side airbag modeling and its application in occupant safety in lateral collisions are presented in this paper. A very detailed model of a folded side airbag has been developed and the simulation of the unfolding of the airbag was compared with special airbag testing results. The kinematics and time-histories of the model are compared with test data and discussed in this paper. The airbag model was then used as a design tool to evaluate the performance of the occupant in side impacts. Advanced finite element dummy models were used in the airbag system level evaluation. The results of the modeling as compared with dynamic sled test data are presented in this paper.