PROJECT SUMMARY The biracial population is the second-fastest growing demographic group in the US. Biracial adolescents also have higher risks of substance use as well as violent behavior, school problems, and poor physical and mental health than many of their monoracial peers. However, little is known about substance use prevention and interventions in this population. Historically, biracial youth have been either ignored in research or their many subgroups have been combined into a single “multiracial” category, potentially obscuring clinically relevant patterns. Moreover, no accepted model explains the factors that increase or decrease the risk of substance use among biracial youth. Discoveries made during the course of the proposed research will help accelerate the refinement of existing prevention and intervention programs for biracial adolescents and emerging adults, and will speed translation of its findings into public health practice. We propose to study the 4 subgroups of biracial youth that our prior research has shown to have the highest risk of substance use, namely biracial White-American Indian, White-Asian, White-Black, and White- Hispanic youth. In doing so, we will also test a newly developed model, the Double Jeopardy Hypothesis, that we propose to explain biracial substance use patterns. According to this model, biracial individuals experience not only the common risk factors for substance use, which are also experienced by monoracial youth but also a second set of risks unique to being biracial in America. This study takes advantage of existing data from two large, longitudinal and nationally representative databases that include adequate numbers of biracial persons to allow the sample to be divisible into subgroups, as well as multiple measures of social determinants of health (e.g., perceived discrimination, racial socialization), substance use, and other behavioral and physical outcomes. The first, Monitoring the Future, followed students from middle-/high-school through age 55 years. The second, the National Longitudinal Study of Adolescent and Adult Health, followed students from age 11 to 42 years. After integrating the two datasets using integrative data analysis to study adolescents and emerging adults ages 13-25 years old (Aim 1), we will determine the onset, prevalence, and developmental trajectories of substance use (i.e., cigarette, alcohol, marijuana, and polydrug use) from adolescence to emerging adulthood (ages 13-25) (Aim 2). Last, we will explore the relationships of common and unique risk and protective factors (in the individual, family, peer, school, and community domains) for substance use among biracial adolescents and emerging adults, examining evidence for the proposed Double Jeopardy Hypothesis (Aim 3). Findings will inform more effective and inclusive prevention approaches for an understudied but rapidly growing sector. If accurate, the Double Jeopardy Hypothesis will provide insight into the li...