This proposal requests a second 5 years of support for a continuing study of over 650 families and children of Mexican origin. During the first 5 years of support, two cohorts of families and children were recruited and followed from 5th through 7th or 8th grades. During the next 5 years, we will continue to follow these families and children as they navigate the adolescent years, a time of high risk for involvement with licit and illicit substances. The research will address four important issues related to the initiation and escalation of alcohol, tobacco, and other drug (ATOD) use. First, the investigation will examine risk for and resilience to ATOD use in a critically important ethnic group in the United States, children of Mexican origin. Mexican Americans living in California will soon become the most populous ethnic group in the state, consistent with national trends for Latinos. Second, the investigation will examine developmental pathways leading to the initiation and escalation of ATOD use from late childhood through adolescence. A developmental approach is generally considered the best strategy for informing the creation of effective intervention programs that can prevent the early initiation of ATOD use, when it is most likely to have severe long-term consequences. Third, the investigation will examine family influences on the initiation and escalation of ATOD use, also considered crucial for early prevention. Finally, the investigation will employ state-of-the-art research methods for studying family influences on the development of ATOD use. Hypotheses will be derived from the family stress model, which proposes that acculturation processes, minority experiences, economic hardship, and neighborhood and school risks will affect parent-parent, parent-child, and sibling and peer relationships. These relationships, in turn, are expected to influence the initiation and escalation of ATOD use and related adjustment problems such as risky sexual behaviors, which increase long-term risk for HIV/AIDs and other STDs. The family stress model also proposes that a set of cultural (e.g., respect, familism), personal (e.g., ethnic identity, self-control), and social (e.g., effective family problem solving) resources will promote resilience to the hypothesized risk factors. The major test of these hypotheses will come during the next 5 years when the children enter adolescence and risk for ATOD use increases dramatically. An important goal of this next phase of the research will be to evaluate how risk factors, protective mechanisms, and ATOD use interrelate in a dynamic manner across the adolescent years. Results of the study are expected to inform the development of more effective and culturally sensitive early prevention programs for an important and understudied population.