PROJECT SUMMARY I am a developmental scientist and Assistant Professor at Brown University’s Center for Alcohol and Addiction Studies. Together with a multidisciplinary mentorship team, I propose a multimethod, intensive longitudinal study of the associations between parental alcohol use (PAU), parent stress and child externalizing disorders (EXT). The proposed research project represents an intentional extension of my research, and this award will serve the dual purpose of facilitating my research independence and expanding the scope of CADRE research in fulfillment of its mission. This award will provide me with protected time, research infrastructure, and mentorship that will allow me to expand my program of research to include a new population (children with severe behavior disorders) and to learn novel methods (alcohol biosensors) that I can incorporate into my research. Moreover, as a developmentally informed addiction scientist, my integration into the CADRE team will broaden the expertise currently represented in the CADRE and permit novel avenues of inquiry in CADRE projects. This research project is aligned with the overarching aims of the CADRE (to advance knowledge of the impact of substance use on chronic disease) and expands the scope of CADRE research in its intergenerational focus on the impact of parental substance use on a chronic child condition. Child EXT, a spectrum of behaviors and disorders including Conduct Disorder and Oppositional Defiant Disorder, are common, chronic, and costly developmental disorders that often cascade into life-course persistent problems. This is especially true for children from low socioeconomic status families who will represent ~60% of the study sample. Parents and parent-child dynamics exert strong influence on child EXT; here we focus on the influences of PAU and parent stress on child EXT trajectories across one month of intensive outpatient treatment for child EXT. We enhance this investigation by exploring parent-child interaction quality as a potentially modifiable mediator linking PAU and stress to EXT. We focus on a diverse, severe clinical sample of children engaged in partial hospitalization treatment to characterize these processes among those at greatest risk for developing cascading, persistent antisocial behaviors. Our multi-informant approach leverages multiple methods that span levels of analysis; an approach that innovates on existing research. The joint support of the CADRE Cores will ensure the successful completion of the proposed project. The REACH Core will assist in the recruitment of a diverse sample, the Clinical Lab Core will provide the requisite supplies, equipment, and technical and scientific expertise to support the proposed project, and the Administrative Core will provide the organizational structure, resources, mentoring support, and initiatives that will facilitate the successful completion of the proposed study and solidify my path to independence.