Animal studies point to the role of two neuropeptides-oxytocin and vasopressin-in the regulation of affiliative behaviors including mating, pair-bond formation, maternal/parenting behavior, and attachment. These findings may have important implications for understanding and treating clinical disorders marked by social deficits and/or disrupted attachment. This review focuses on advances made to date in the effort to forge links between basic and clinical research in the area of neuropeptides and social behavior. The literature on oxytocin and its involvement in stress response, affiliation, and prosocial behavior is reviewed, and the implications of these findings for such disorders as autism as well as other social and stress-related disorders including social phobia, post-traumatic stress disorder, and some personality disorders are considered. Finally, unresolved issues and directions for future research are discussed.