Focuses on the developmental periods of infancy, childhood, and adolescence to offer illustrations of the advantages of using developmental theory and research to establish targets for research on intervention, assessment and treatment planning, and evaluation of effective strategies for prevention of childhood and later adult disorders. The importance for training clinical graduate students in developmental approaches to research is stressed, and hopes for a future of mutual contributions of developmental and clinical psychology are expressed in light of the fact that, after a troubled history of isolation from one another and even active denigration of one another's goals and methods, developmental and clinical psychology are exhibiting joint recognition of the advantages of collaborative research.