Psychoanalysis continues to make important contributions to basic clinical understanding of adaptive and maladaptive psychological development, and particularly to the understanding of depression and its treatment. This paper demonstrates that a basic theoretical conceptualization, central to many of Freud's fundamental contributions, has provided the basis for a wide range of contemporary psychoanalytic and nonpsychoanalytic formulations of personality development and organization; for understanding various forms of psychopathology in adults as deriving from disruptions of normal developmental processes, especially personality disorders and depression; and for conducting research on psychotherapeutic process and outcome in both brief and long-term intensive treatment.