To determine patterns of risk among teenage drivers. Review and synthesis of the literature. On most measures, crash rates during the teenage years are higher than at any other age, for both males and females. Risk among teenagers varies greatly by driving situation; it is particularly low in some situations (e.g., the learner period) and particularly high in others (e.g., right after licensure, late at night, with passengers present). In some of these high-risk driving situations, risk is elevated for drivers of all ages (e.g., late night driving), in others risk is elevated more for teens than adults (e.g., driving after consuming alcohol), and in others the risk is unique to teen drivers (e.g., having passengers). These varying patterns of risk form the basis for graduated licensing systems, which are designed to promote low-risk and discourage high-risk driving.