For lesbian, gay, bisexual, or queer (i.e., sexual minority [SM]) youth, coming out is an important developmental milestone and is typically associated with positive well-being. However, coming out in high school may entail a higher risk of school-based victimization. Due to the greater risk of homophobic bullying, the implications of being out in adolescence and well-being later in adulthood remain unclear. Using data from a national probability survey (Generations Study) of three distinct age cohorts of SM adults (N = 1,474) in the United States, this study (a) examined how being out at school in adolescence affects general well-being in adulthood and (b) SM-specific well-being in adulthood, and (c) examined if these associations differ by cohort. Results from multivariate regression analyses demonstrated that being out in adolescence was not significantly associated with general well-being, but was significantly associated with SM-specific well-being: higher rates of identity centrality and community connectedness, and lower rates of internalized homophobia. There were no cohort differences in the associations between outness in high school, general well-being, and SM well-being. The findings from this national probability sample of SM adults provide novel insight into implications of being out across the life course, including the positive implications of being out at school in adolescence for SM-specific well-being in adulthood.