This Article offers a new interpretation of the United States Constitution’s republican guarantee and theorizes its protection of a fundamental right to education. Courts and education law scholars have identified the republican guarantee as a plausible source of educational rights but have not detailed how. Drawing on recent work by legal scholars, historians, political scientists, and philosophers, this Article reinterprets the guarantee as the federal government’s obligation to secure freedom as nondomination, and it argues that excellent, equitable public education is necessary to fulfilling this duty. Nondomination, a robust conception of freedom, is freedom from subjection to the will of others, protecting against potential interference and not merely against actual interference. Nondomination has deep roots in American social movements and in the antislavery constitution, and it requires active government answerable to all people, prioritizing laws and institutions that constrain private as well as public power. Under this theory of the republican guarantee, education has a potent role in overcoming the costs of domination, which include psychological costs— such as the atomization of citizens and their failure to see each other as equals—and material costs—such as unpreparedness for democratic participation and individual pursuit of the good life. Although a nondomination guarantee requires strong institutions outside of schools, education has a further role in equipping people with the tools to resist domination when other institutions fail to prevent it. In laying out this theory, this Article addresses both the conventional teaching that the republican guarantee raises nonjusticiable political questions and the genuine conceptual challenge of lawmaking under an ongoing antidomination duty.