Project Summary Marijuana use among youth has been increasing, with considerably enlarged disparities across racial/ethnic groups. Racial minorities like African American (AA) adolescents are more likely to report marijuana use than their White peers. Marijuana use during adolescence can harm brain development and lead to other substance abuse and adverse health outcomes. In order to identify potential targets for interventions to reduce health disparities, there is a critical need to distinguish risk and protective factors for marijuana use that are specific to race and ethnicity. With a shifting legal environment for marijuana use in the United States and more adults supporting marijuana legalization, it is estimated that 8.2% of mothers and 9.6% of fathers living with adolescent offspring reported past-year marijuana use. The family environment is a major driver of youth development, and racial and ethnic families often experience greater exposure to systemic oppression (e.g., institutional and interpersonal racism, bias, and discrimination) and higher social inequality than their White peers, resulting in acute and chronic stress. Therefore, we hypothesize that parental marijuana use independently predicts offspring marijuana and other substance use, and intergenerational effects of marijuana use may be stronger among racial and ethnic families, especially among AA families. The overarching goal of this mixed-methods sequential explanatory study is to assess racial disparities in relationships between parental marijuana use and youth substance use. In Aim 1, we will leverage a longitudinally national survey with 5 waves of parent and offspring data (n≈3,272) to examine the intergenerational association between G1 marijuana use and subsequent G2 marijuana, vaping, tobacco, and other illicit drug use across distinct racial/ethnic groups (AAs, H/Ls vs. non-Hispanic Whites). In Aim 2, we will assess moderation and mediation effects from marijuana legalization status and other determinants (e.g., discrimination and psychological distress) across racial/ethnic groups. In Aim 3, we will conduct semi- structured interviews of parent marijuana users and their offspring (n≈96 each) to qualitatively examine the intersections of parent influences and policy change on youth substance use. Analyses of intergenerational and longitudinal surveys and semi-structured interviews will be fully integrated to complement each other and provide more robust findings. This study is innovative in its focus on assessing racial disparities in the intergenerational transmission of marijuana use in AAs and H/Ls, two NIH-designated health disparity populations. This study is also timely in responding to the rapidly shifting policy environment, rising marijuana use among youth and adults, and growing disparities by racial/ethnic group, with unknown etiology on the intergenerational drug use by racial/ethnic groups. The findings will inform the development of a future R01 to test tailored strategies to prevent youth marijuana and other substance use and reduce health disparities. 1

Project Narrative This will be the first intergenerational study to assess racial disparities in the influence of parental marijuana use on youth marijuana and other substance drug use in African Americans and Hispanics/Latinos, two NIH- designated health disparity populations. We will further assess the effects of marijuana legalization and other determinants on intergenerational drug use behaviors by racial and ethnic groups. This mixed-methods sequential explanatory study will be pursued by integrating analyses of intergenerational and longitudinal surveys and semi-structured interviews