Aim To discuss the contributions and future course of the psychological science of addiction. Background The psychology of addiction includes a tremendous range of scientific activity, from the basic experimental laboratory through increasingly broad relational contexts, including patient–practitioner interactions, families, social networks, institutional settings, economics and culture. Some of the contributions discussed here include applications of behavioral principles, cognitive and behavioral neuroscience and the development and evaluation of addiction treatment. Psychology has at times been guilty of proliferating theories with relatively little pruning, and of overemphasizing intrapersonal explanations for human behavior. However, at its best, defined as the science of the individual in context, psychology is an integrated discipline using diverse methods well-suited to capture the multi-dimensional nature of addictive behavior. Conclusions Psychology has a unique ability to integrate basic experimental and applied clinical science and to apply the knowledge gained from multiple levels of analysis to the pragmatic goal of reducing the prevalence of addiction.