ABSTRACT Anti-gay attitudes have declined in the U.S. The magnitude, speed, and demographic scope of this change have been impressive especially in comparison with prejudice against other marginalized groups. We develop a philosophically-informed psychological account of the unique decline in anti-gay bias in the context of important cultural and political conditions. We highlight two key psychological mechanisms: interpersonal connection and social category classification. First, many people have discovered that a close friend, family member, or admired individual is gay, motivating them to identify the harm and discrimination faced by the individual they know, and catalyzing moral consistency reasoning such that they generalize this interpersonal insight to strangers. Second, many people have taken an essentialist stance toward social categories, including sexual orientation, leading them to infer that being gay is genetically determined and not subject to free choice or moral responsibility, nor mutable and worth attempting to change. We contrast this with the relationship between essentialism and attitudes toward women and people of color, and provide an account of the difference. This psychological account has implications for the future decline of anti-gay attitudes, in the U.S. and other countries, along with the nascent decline of anti-trans attitudes.