This paper presents a theory of rational addiction, where rationality is defined as a consistent plan to maximize utility over time. The authors argue that addiction, even strong one, can be rational in the sense of involving forward-looking maximization with stable preferences. They develop a model of rational addiction that considers the dynamic aspects of addictive consumption and the conditions that determine whether steady-state consumption levels are stable or unstable. The model shows that strong addictions are often rational and that "cold turkey" is used to end them. The theory also implies that addicts often go on binges, respond more to permanent than temporary changes in prices of addictive goods, and that anxiety and tensions can precipitate an addiction. The authors also show that consumption of addictive goods responds less to temporary changes in prices than to permanent changes. The analysis builds on the model of rational addiction introduced by Stigler and Becker (1977) and developed further by Iannaccone (1984, 1986). The paper also discusses the effects of life cycle events on the demand for addictive goods and the importance of unstable steady-state consumption levels in explaining rational addiction. The authors conclude that rational addiction involves a consistent plan to maximize utility over time, and that the theory provides new insights into addictive behavior.This paper presents a theory of rational addiction, where rationality is defined as a consistent plan to maximize utility over time. The authors argue that addiction, even strong one, can be rational in the sense of involving forward-looking maximization with stable preferences. They develop a model of rational addiction that considers the dynamic aspects of addictive consumption and the conditions that determine whether steady-state consumption levels are stable or unstable. The model shows that strong addictions are often rational and that "cold turkey" is used to end them. The theory also implies that addicts often go on binges, respond more to permanent than temporary changes in prices of addictive goods, and that anxiety and tensions can precipitate an addiction. The authors also show that consumption of addictive goods responds less to temporary changes in prices than to permanent changes. The analysis builds on the model of rational addiction introduced by Stigler and Becker (1977) and developed further by Iannaccone (1984, 1986). The paper also discusses the effects of life cycle events on the demand for addictive goods and the importance of unstable steady-state consumption levels in explaining rational addiction. The authors conclude that rational addiction involves a consistent plan to maximize utility over time, and that the theory provides new insights into addictive behavior.