The potential effects of passenger air bag deployment on an out-of-position three-year-old child dummy and on a three-year-old child dummy in a child restraint system are two of the items considered in the development of an automotive passenger air bag restraint system. In order to increase our understanding of the passenger air bag and three-year-old dummy interaction, we have developed a three dimensional computer model of a three-year-old child dummy. The dummy model has a compressible sternum and a multi-segment representation of the neck which helps improve the predictive capabilities of the neck criteria. The dummy properties needed as inputs to the occupant model were all experimentally determined. An energy technique was used for separating the elastic, damping and friction components for each joint.Three HYGE sled test cases were simulated to validate the model. The three cases are the child dummy with a passenger air bag: in a three-point belt with a booster seat, in a shield-type child seat, and out-of-position. For all cases, the passenger air bag is modeled with finite elements. Based on the comparison of the model and test results, the dummy model appears to be a reasonable representation of the actual three-year-old child air bag dummy which can be used during the development of an air bag restraint system for comparing design alternatives.