Abstract: The U.S. Supreme Court’s decision in Obergefell v. Hodges establishing marriage equality for same-sex couples marks a major shift in recognizing gay, lesbian, and bisexual people as a central part of the fabric of American society. Obergefell also marks the passing of the torch from “LGB” to “T”; the next civil rights frontier belongs to transgender people, for whom key barriers still remain. In January 2015, a transgender woman filed an equal protection challenge to a provision of the Americans with Disabilities Act (“ADA”), which explicitly excludes several medical conditions closely associated with transgender people. In support of this challenge, lawyers for the plaintiff (and co-authors of this Article) advance a novel argument: transgender people are a “suspect” or “quasi-suspect” class entitled to heightened scrutiny. The authors further argue that the ADA’s transgender exclusions are unconstitutional no matter what level of scrutiny applies because moral animus against transgender people is not a legitimate basis for lawmaking. This equal protection challenge paves the way for the extension of disability rights protection to transgender people under the Rehabilitation Act, Fair Housing Act, and state anti-disability discrimination laws that mirror the ADA. It also marks a new break for equality law—reaching far beyond disability rights to all laws that single out transgender people for disparate treatment. This challenge also informs the broader theoretical debate over the relationship between identity and impairment, and diagnosis and discrimination.