The authors analyze the expression of sexualities in the contemporary United States using data about disclosure on social media. Through the Facebook advertising platform, the authors collect aggregate counts encompassing 200 million Facebook users, 28 percent of whom disclose sexuality-related information. Stratifying by age, gender, and relationship status, the authors show how these attributes structure the propensity to disclose different sexual identities. There is a large generational difference; younger social media users share their sexualities at high rates, while for older cohorts marital status substitutes for sexual identity. Consistent with gendered expectations, women more often express a bisexual interest in men and women; men are more explicit about their heterosexuality. The authors interpret these variations in sexuality disclosure on social media to reflect the salience of sexual identity, intersected at times with availability. This study contributes to the sociology of sexuality with a quantitative analysis, using novel digital data, of how sexuality is signaled socially.