Project Summary Sexual minorities exhibit significantly higher rates of substance use (SU) and substance use disorders (SUD) compared to their heterosexual counterparts. The vast majority of SU research among sexual minorities, however, has focused on urban populations with little work comparing patterns of SU between rural and urban dwelling sexual minorities. Past work with heterosexual populations has observed strong differences in SU patterns based on urbanicity. Utilization and success of SU treatment programs have also been found to vary widely based on urbanicity of residence, with rural environments suffering from a lack of treatment options and an increased burden of SUD. Additionally, chronic SU has been linked to a number of chronic physical health problems (e.g. cardiovascular disease). Consistent with their higher rates of SU, both sexual minority populations and rural heterosexual populations experience a disproportionate burden of SU-associated chronic diseases. It is therefore likely that SU and chronic disease rates will be even further elevated among understudied rural sexual minorities, making them an extremely high-risk group. Given their potential risk, it is vital to develop a better understanding of how SU, unmet treatment need, and SU-associated chronic diseases differ between rural and urban dwelling sexual minority. The proposed R03 Small Research Grant Program will utilize data from a nationally representative study, namely the National Survey on Drug Use and Health (NSDUH). This survey is an annual cross-sectional household survey of non-institutionalized individuals living in the United States and includes measures of alcohol, tobacco, and drug use, substance use treatment, and a number of SU-associated chronic diseases (e.g. cardiovascular disease, cancer). We will analyze data from all years of NSDUH that have data on sexual identity and are available at commencement of analyses (2015-2020). Data will be used to assess disparities in the aggregate prevalence of focal variables and variations in these disparities by year (via time-varying effects) in all three specific aims: 1) assess disparities in SU and SUD between rural and urban sexual minorities and determine whether sexual orientation disparities in SU vary by urbanicity; 2) delineate differences in treatment utilization and unmet treatment need among rural versus urban sexual minorities and determine whether disparities in treatment between heterosexual and sexual minority populations vary by urbanicity; and 3) determine whether SU-associated chronic disease disparities exist between rural and urban sexual minorities and whether sexual orientation disparities in chronic diseases vary by urbanicity. This proposal is the first step in a program of research which ultimately aims to develop behavioral and biomedical interventions tailored to the specific needs of rural and urban sexual minority populations.