Behavioral addictions, such as pathological gambling, kleptomania, pyromania, compulsive buying, and compulsive sexual behavior, represent significant public health concerns and are associated with high rates of psychiatric comorbidity and mortality. Although research into the biology of these behaviors is still in the early stages, recent advances in the understanding of motivation, reward, and addiction have provided insight into the possible pathophysiology of these disorders. Biochemical, functional neuroimaging, genetic studies, and treatment research have suggested a strong neurobiological link between behavioral addictions and substance use disorders. Given the substantial co-occurrence of these groups of disorders, improved understanding of their relationship has important implications not only for further understanding the neurobiology of both categories of disorders but also for improving prevention and treatment strategies.