Process, mechanism, and explanation related to externalizing behavior in developmental psychopathology.

Advances in conceptualization and statistical modeling, on the one hand, and enhanced appreciation of transactional pathways, gene-environment correlations and interactions, and moderator and mediator variables, on the other, have heightened awareness of the need to consider factors and processes that explain the development and maintenance of psychopathology. With a focus on attentional problems, impulsivity, and disruptive behavior patterns, I address the kinds of conceptual approaches most likely to lead to advances regarding explanatory models in the field. Findings from my own research program on processes and mechanisms reveal both promise and limitations. Progress will emanate from use of genetically informative designs, blends of variable and person-centered research, explicit testing of developmental processes, systematic approaches to moderation and mediation, exploitation of "natural experiments," and the conduct of prevention and intervention trials designed to accentuate explanation as well as outcome. In all, breakthroughs will occur only with advances in translational research-linking basic and applied science-and with the further development of transactional, systemic approaches to explanation.