Sexual minority women (i.e., women who identify as lesbian, bisexual, or other non-heterosexual orientations) report more hazardous drinking compared to heterosexual women. Sexual minority stress (SMS), or experiences related to sexual orientation-based discrimination and marginalization, have been implicated as contributing to these disparities. The association between sexual minority stress and alcohol use has been supported in cross-sectional, and to a limited extent, longitudinal studies. Few studies, however, have examined associations between SMS and alcohol use in sexual minority women's daily lives. Young sexual minority women (age 18-35; N = 321) were recruited to participate in a 14-day daily diary study in which they reported each morning on their SMS and alcohol use (drinking or not; drinking quantity; alcohol consequences) from the previous day. SMS was operationalized in four ways (global negative SMS experiences, specific SMS events, concealment of identity, discrimination). Results from concurrent multilevel models revealed that on days when sexual minority women experienced more global negative SMS, any specific SMS event, or discrimination, they were more likely to drink. Further, prospective models indicated that participants drank more and were more likely to report binge drinking on the day after they experienced at least one SMS event. These findings extend prior research by demonstrating that the association between SMS and alcohol use extends to the daily level of analysis among sexual minority women. Understanding the connection between SMS and alcohol use among sexual minority women is imperative to developing culturally tailored interventions to improve the health and well-being of this at-risk group. (PsycInfo Database Record (c) 2021 APA, all rights reserved).