This paper studies a school district that was federally mandated to adopt a race-blind lottery system to fill seats in its oversubscribed magnet schools. The district had previously integrated its schools by conducting separate admissions lotteries by race to offset its predominantly black applicant pools. The change dramatically segregated subsequent magnet school cohorts. More segregated schools enroll students with lower baseline achievement and employ lower valueadded teachers. Segregation is further exacerbated by “white flight” as white students transfer out of the district after attending more segregated schools. Ultimately, mandated segregation decreases student test scores and college attendance.