In the context of health, safety, and environmental decisions, the concept of risk involves value judgments that reflect much more than just the probability and consequences of the occurrence of an event. This article conceptualizes the act of defining and assessing risk as a game in which the rules must be socially negotiated within the context of a specific problem. This contextualist view of risk provides insight into why technical approaches to risk management often fail with problems such as those involving radiation and chemicals, where scientific experts and the public disagree on the nature of the risks. It also highlights the need for allowing the interested and affected parties to define and play the game, thus emphasizing the importance of institutional, procedural, and societal processes in risk management decisions.