Project Summary One of the most debilitating and pervasive high-risk ecologies children encounter in American society is poverty and its many correlates, such as compromised parenting, deprived neighborhoods and schools, deviant peer clustering, and poor nutrition and medical care. Despite the greater risk of a host of maladaptive outcomes associated with poverty, few studies have prospectively examined young adult adjustment for children born into poverty beginning at age 2. Even fewer longitudinal trials initiated in early childhood have examined the impact of a brief and repeated family intervention in preventing alcohol and drug use disorder (ADUD). The Early Steps Multisite (ESM) prevention trial was specifically designed to address the needs of children and families living in poverty, often marked by compromised parenting and parent well-being. Initiated at child age 2 and follow-ups at nine ages through age 16, the ESM sample was recruited from WIC centers in three geographically, socioeconomically, and ethnically diverse communities: Pittsburgh, PA; Charlottesville, VA; and Eugene, OR. To increase the number of sample families at risk for later ADUD, eligibility was restricted to WIC families with additional socioeconomic, family, and child risk factors. Families were randomly assigned to be offered a yearly FCU intervention, including adapted and tailored family management interventions. The children and families were initially assessed at child age 2 and then yearly through age 10.5, using a multi-agent and multi-method strategy that included direct observations of family interaction in most years, and subsequently followed at ages 14 and 16. In the current application, we are proposing to continue following this multiethnic sample (N=731) of youth who are transitioning to adulthood, at ages 19 and 21. With genotyping on an extensive contemporary array, prospective data on neighborhood risk and racial/ethnic disparities, we propose to examine direct, interactive, and cascading effects of child, genetic, family, peer, and neighborhood factors on ADUD and related outcomes; lasting effects of the Family Check-Up on ADUD and related problem and prosocial behavior; and moderating effects of the Family Check- Up’s effectiveness.