This paper describes how safety risk is considered in decision making by the National Highway Traffic Safety Administration (NHTSA) of the U.S. Department of Transportation. The mission and goal of NHTSA is to increase highway safety and to reduce the risk of deaths and injuries occurring in highway accidents through improvements affecting drivers and vehicles. Working from the premise that there is no single “cause” of an accident, the agency must address both the individual contributing factors as well as the interactions among these factors. This process involves defining the safety risks for road travelers, considering alternative measures to reduce these risks, and assessing the benefits and costs for each alternative. Because of the complexities involved as well as the many gaps in knowledge about accident causation, the agency does not base its program decision strictly on quantitative analysis, but considers the latter to be an aid in support of management judgment.