The joint contributions of psychotherapist and researcher to strengthening the knowledge base of psychopathology has been too often ignored in the antagonism that exists between the two camps. This article examines the contributions of both groups to the emerging science of developmental psychopathology. The role of single case observations in the origins of this multidisciplinary perspective is highlighted. The constructs of stress, coping, risk, vulnerability, and protective factors are reviewed as central themes in the formulation of research in developmental psychopathology. A research case example, Project Competence, is provided to illustrate the relevance of these concepts in studying the factors that influence the quality of adjustment in children and adolescents. The implications of such research findings for therapeutic interventions and future research on stress-resistance are discussed, with emphasis on the benefits to be gained by both therapist and researcher from the study of risk and protective factors in the development of competence and psychopathology.