Brown v. Board of Education established equality as a central commitment of American schools but launched more than a half century of debate over whether students from different racial, religious, gender, and ethnic backgrounds, and other lines of difference must be taught in the same classrooms. Brown explicitly rejected state-ordered racial segregation, yet neither law nor practice has produced a norm of racially integrated classrooms. Courts restrict modest voluntary efforts to achieve racially mixed schools. Schools in fact are now more racially segregated than they were at the height of the desegregation effort. Talk of this disappointing development dominated the events commemorating the fiftieth anniversary of the Brown decision. Instead of looking at the composition of schools and classrooms, policy-makers measure racial equality in American schooling by efforts to reduce racial differentials in student performance on achievement tests, and those efforts have yielded minimal success. Historians question whether the lawyers litigating Brown undermined social changes already in the works or so narrowed reforms to the focus on schools that they turned away from the pursuit of economic justice. Commentators have even questioned whether the Court’s decision itself ever produced real civil rights reform. Although Brown focused on racial equality, it also inspired social movements to pursue equal schooling beyond racial differences, and it yielded successful legal and policy changes addressing the treatment of students’ language, gender, disability, immigration status, socioeconomic status, religion, and sexual orientation. These developments are themselves still news, inadequately acknowledged and appreciated as another key legacy of Brown. Yet here, too, judges, legislators, school officials, experts, and parents disagree over whether and when equality calls for teaching together, in the same classrooms, students who are or who are perceived to be different from one another. Parents and educators have at times pushed for separate instruction and at times for instructing different students side by side. As the twenty-first century proceeds, equality in law and policy in the United States increasingly calls for mixing English-language learners with English-speaking students and disabled with non-disabled students, but students’ residential segregation and school assignments often produce schools and classrooms divided along lines of race, ethnicity, and socio-economic class.