U.S. federal law prohibits discrimination on the basis of sex in education. U.S. case law also applies the prohibition of sex discrimination to incidents motivated by a person’s sex or gender, including gender identity and expression. Enumerated nondiscrimination, school-based policies that include gender identity and expression are among the foundational policies advocated for by researchers and practitioners who aim to make schools safer for transgender and gender nonconforming students. These policies serve as a foundation for all other interventions or policies that may be implemented in schools to increase safety for transgender and gender nonconforming students. Further, enumerated nondiscrimination policies provide students with a clear understanding of their rights at school, and they provide school personnel with grounding to prevent and intervene in gender-based discrimination. Research finds that transgender and gender nonconforming students experience high levels of stigma in schools (manifested as discrimination, stigma-based bullying), and that these school-based experiences are associated with compromised educational outcomes in addition to disparities in behavioral, physical, and psychological health. Students in schools that have enumerated nondiscrimination policies report less bias stigma-based bullying attributed to gender identity and expression compared to students in schools with nonenumerated policies. Further, students are more likely to report that teachers intervene in stigma-based bullying attributed to gender identity and expression in schools that have enumerated nondiscrimination policies compared to those that do not. Finally, studies find that nondiscrimination policies that include gender identity and expression attenuate the negative consequences of stigma for students.