The recent real-world experience with the frontal airbags and their sometimes unfortunate interaction with small size adults and children led to the analytical efforts and the results reported in this paper.The focus of this paper is an analytical study investigating the side impact protection performance of side airbags in interaction with, out-of-position occupants. The study evaluates interaction of the two extreme size occupants including a 3 year old child, and a small 5th percentile adult female. The objective is to identify any potential problems with the side impact airbags in real world scenarios. To date, a considerable amount of research has been invested in developing and evaluating occupant protection systems for both frontal and side impacts. However, the majority of this research has focused on the 50th percentile adult male occupant size, who is properly seated in his seat. The current study validates the computer model using available test data and then assesses the side impact protection performance of the side airbags for the selected conditions.A computer modeling system, SIFEM, is used to simulate various side impact scenarios of interest and to evaluate several vehicle designs. Candidate designs include currently on the market side airbag systems and those reported in technical literature. System performance is measured in terms of injury criteria (e.g., HIC, TTI, peak chest acceleration, peak pelvic acceleration, occupant kinematics, etc.).SIFEM computer model is designed to take advantage of finite element and lumped mass modeling techniques. The model simulates interior occupant protection systems including padding, and airbag systems. Airbag system with user-selected bag shape and inflator flow characteristics are modeled. Simplified stretch and deployment algorithms model the bag deployment and its interaction with the occupants. Bagslap, catapult (membrane) and contact pressure phases are also modeled.