PROJECT SUMMARY/ABSTRACT In response to the Notices of Special Interest on Research on the Health of Sexual and Gender Minority Populations (NOT-MD-19-001) and Public Policy Effects on Alcohol-, Cannabis-, Tobacco-, and Other Drug- Related Behaviors and Outcomes (NOT-AA-21-028), this project will identify trajectories of alcohol misuse by sexual orientation and their associated health consequences. We will also examine risk and protective factors across individual, social, and policy domains. Sexual minorities are at heightened risk of alcohol misuse; however, existing research is often based on a static and unidimensional construct of sexual orientation rather than a fluid and multidimensional construct of sexual orientation, despite evidence indicating sexual orientation fluidity is common, especially among sexual minorities. Prior work has shown alcohol misuse and alcohol use disorder (AUD) symptoms are more prevalent and more severe among sexual minorities than heterosexuals. There is a lack of population-based longitudinal studies of alcohol misuse trajectories and related negative health consequences based on a fluid and multidimensional construct of sexual orientation. Additionally, studies examining risk and protective factors for alcohol misuse among sexual minorities have largely focused on individual-level factors and neglected factors at the social and policy level. There is a need to expand this research and draw on concepts from the Social Ecological Model to include upstream risk and protective factors, such as those at the social and policy level. To address these gaps, this project will use longitudinal data from a sample of U.S. adolescents and adults based on six waves of the Population Assessment of Tobacco and Health study (n=45,971; 2013-2021). This study design will allow us to explore changes in alcohol misuse based on sexual orientation before and after COVID-19 onset. Our study aims to: (1) Identify alcohol misuse trajectories over an 8-year period and determine if these associations differ by sexual orientation (a) concordance vs. discordance, and (b) stability vs. fluidity. We will also examine potential heterogeneity in risk by age, sex, race, ethnicity, and gender identity and compare changes in alcohol misuse before and after COVID-19 onset by sexual orientation. (2) Examine (a) how variation in alcohol misuse trajectories shape negative health-related consequences (e.g., AUD symptoms, other substance use disorder symptoms, polysubstance use, and negative physical health consequences) and (b) whether this differs across sexual orientation subgroups, by sexual orientation discordance vs. concordance, and sexual identity fluidity vs. stability. (3) Examine longitudinal relationships of individual- (e.g., internalizing symptoms), social- (e.g., degree of social interaction), and policy-level (e.g., antidiscrimination laws) protective/risk factors with trajectories of alcohol misuse and negative alcohol-related health c...