Purpose: School administrators and policy makers live in a complex, changing policy universe in which there are many competing demands and political pressures. Rarely is there much time to think about sensitive issues of long duration that are not part of the immediate demands they face. This article is about such an issue, a question that will deeply influence the future of schools and communities but which is usually ignored--the increasing separation of large sectors of our student bodies into intensely segregated schools with unequal educational opportunity. Research Methods: The data analyzed come from the National Center for Education Statistics, Public Elementary/Secondary School Universe, which contain demographic data about all public schools since the late 1980s. We rely on two measures of segregation, concentration and exposure/isolation index, to assess its current status and change over time in the nation's public schools. Findings: This article describes the vast transformation of the nation's school population since the civil rights era. As diversity spreads, so too does segregation by race and often class, including into suburbia in many large metropolitan areas. As a legacy of "Brown," Black students are still more desegregated in the South than any other region of the country, but both Black and Latino students are experiencing rising segregation. Implications: We conclude with recommendations about possible responses educational leaders might pursue to make the promise of "Brown" a reality in the 21st century. Desegregation properly implemented can help equalize educational opportunities and prepare young Americans for the diverse society in which they will live.