Aggressive and antisocial behavior (e.g., fighting, destroying property, stealing) among children and adolescents comprise one of the most expensive mental health problems in the United States and the most frequent basis of referral to clinical services for children. Alan Kazdin has drawn on basic and applied research in learning and cognition to develop two effective evidence-based interventions for these children that improve child functioning at home, at school, and in the community. He has conducted randomized trials with inpatient and outpatient children to develop these interventions, evaluated treatment processes that contribute to therapeutic change, and examined the role of child, parent, and family factors that influence and are influenced by treatment. Kazdin’s current focus is on models of delivering treatment that can reach the majority of children in need of treatment but who do not receive any services. His work also seeks to help redress disparities in care among diverse groups. Kazdin is the founding editor of the Association for Psychological Science (APS) journal Clinical Psychological Science and a recipient of the APS James McKeen Cattell Fellow Award for his lifetime of significant intellectual achievements in applied psychological research.