So important is the perspective of development for understanding psychopathology that it spawned a new discipline-"developmental psychopathology"-which has seen remarkable advances since its introduction,, but has yet to completely fulfill its promise. To do this requires maintaining a thoroughgoing developmental perspective. When we take development seriously, there are implications for how we understand psychopathology, describe and conceptualize the origins and course of disorder, and interpret research findings. From this perspective, disorders are complex products of development; for example, we can view neurophysiological associates of disorder not as causes but as markers, the development of which we need to understand. Research on developmental psychopathology requires an examination of the history of problem behavior from early in life, and it unites multiple features of adaptation and maladaptation (contextual, experiential, physiological, and genetic).