More Canadian children die of road traffic injuries than of any other cause. Nonuse and misuse of child restraints is common and leads to preventable severe injuries or deaths. This article, intended for clinicians interested in injury prevention counselling, advocacy, research, and treatment of child occupants in car crashes, reviews current knowledge about child safety seats and discusses controversies related to their use. Children should sit in the back seat of a vehicle and should be properly restrained in a current age- and size-appropriate device (rear-facing infant seat, child safety seat, booster seat, or lap and shoulder seat belt) that is properly adjusted. The centre rear seat is safer than side positions, but a lap belt alone should be avoided. The age at which children should start sitting in a forward-facing position is controversial. Children should be seated away from air bags. Resources to aid in patient counselling are described.