PROJECT SUMMARY / ABSTRACT One in five women and one in fourteen men in the US have been raped, with four out of five rape survivors reporting that alcohol or substance was involved at the time of the violence. Current prevention efforts are hampered by a limited understanding of the gendered and developmental origins of these health crises. Innovative epidemiologic science that integrates psychological and developmental determinants of sexual violence and alcohol use with cutting edge social network and social norms research is critical for advances in prevention efforts. This Mentored Research Scientist Development K01 Award is designed to increase the candidate’s capacities to undertake innovative social network analyses to provide important insights into the gender socialization processes that occur in adolescence and contribute to alcohol use and sexual violence behavior across the lifecourse. The proposed activities will take place alongside a strong and dedicated training committee comprised of globally renowned experts and will extend the candidate’s existing expertise in social epidemiology to include: social and developmental psychology, adolescent alcohol epidemiology, longitudinal social network analysis, and multilevel structural equation modeling. Research activities will involve social network and structural equation modeling techniques using secondary data from a nationally-representative prospective cohort study. Three specific aims are proposed: Aim 1) Longitudinally examine the relationship between individual gender expression, alcohol use, and sexual violence; Aim 2) Assess contribution of normative gender expression within peer groups to variation in alcohol use and sexual violence outcomes; Aim 3) Identify latent classes of adolescents at greatest risk for alcohol use and sexual violence, and the social network processes (selection and influence) that moderate risk. Research significance includes: a) identification of novel and developmentally-specific mechanisms that explain sex-disparities in alcohol use and sexual violence in adolescence; b) identification of typologies of adolescent peer groups at highest risk for both alcohol use and sexual violence. These findings will provide new avenues for prevention efforts to address the developmental origins of sex-disparities in alcohol use and sexual violence. Research innovations include: a) social network algorithms to identify peer groups, used within multilevel models; b) a novel, validated measure of gender expression; c) an integrated multilevel lifecourse framework of adolescent socialization processes linked to alcohol use and sexual violence. Findings from this work will inform a future survey-based R01 among younger adolescents to further elucidate the social psychological processes and normative environments in adolescent peer groups that impact alcohol use and sexual violence, as modified by racial, sexual, and gender minority status. This work responds to the NIAAA...