National studies have not analyzed sexual identity disparities in high school completion, college enrollment, or college completion in the United States. Using Add Health data, we document the relationship between adult sexual orientation and each of these outcomes. Many sexual minority respondents experienced disadvantages in adolescent academic achievement, school experiences, and social environments. This translates into educational attainment in complex, gendered ways. We find that the socially privileged completely heterosexual identity predicts higher educational attainment for women, while for men it is often a liability. Mostly heterosexual and gay identities are educationally beneficial for men but not women. There are college completion disparities between gay and mostly heterosexual women and their completely heterosexual counterparts. Bisexual respondents, especially women, have particularly problematic outcomes. Adolescent experiences, attitudes, and social contexts explain some of these differences. From adolescence through college, sexual minority groups, but especially females, need intervention to reduce substantial educational disparities.