|Abstract:||Drug addiction is a worldwide epidemic. To reduce its spread, understanding the nature of addiction is crucial and possible treatments have to be developed. Current models of drug addiction only explain why addiction is overwhelming and cannot be overcome. Instead we focus on the dynamic of addiction, which includes rehabilitation and relapse. The model identiﬁes the combination of factors that may defeat addiction. Thus, our model can provide not only a more complete description of addiction as a process but will also be useful for studying and evaluating possible treatments.