For the past five years, the Road Safety and Motor Vehicle Regulation Directorate of Transport Canada has conducted studies of motor vehicle collisions which have resulted in air bag deployments. Canada enjoys high usage of seat belts and, consequently, the vast majority of occupants in the crashes under study were fully restrained. This provided an opportunity to evaluate the effectiveness of air bags as supplemental restraint systems. Results from this process demonstrated that thresholds set by manufacturers for air bag deployment were generally lower than necessary to protect fully restrained occupants. Furthermore, the major drawback of first generation air bags was their aggressivity which often gave rise to air bag-induced injuries to belted occupants. Now, many 1998 vehicles have been equipped with “depowered” air bags. The present paper provides a brief overview of the collision experience with air bags in Canada, and presents some preliminary results from in-depth studies of real world crashes involving second generation air bags.