The development of abnormally aggressive human behavior is complex and multifactorial. Aggressive patterns of behavior often begin early in life and, once established, are notorious for their resistance to change, which has led some to believe that environmental interventions offer little hope for significant reductions in the prevalence of violent behavior in our society. Recent findings from research in the field of developmental psychopathology, however, have shed some new light on this very old problem. This paper specifically reviews the attachment literature and interprets it in the context of what has already been learned from research in epidemiology and behavioral genetics on environmental contributions to aggression over the life span. Environmental factors may influence the development of aggression by affecting children's early relationships with primary caregivers or by limiting opportunities for children to engage in positive relationships with caring adult figures. Longitudinal studies directly correlating early attachment relationships with levels of aggression in later childhood have been limited in number but suggest that insecure early attachment relationships may predispose children to the development of abnormally aggressive behavior, particularly when such relationships represent the entirety of their early social experience. Interventions aimed at either enhancing parent-child relationships or providing opportunities for alternative relationships with caring adult figures, particularly in high-risk settings, may help to prevent abnormally aggressive behavioral outcome.