Single-sex education describes a diverse range of situations, including individual classes, programs after school, required programs, voluntary programs, and programs to remedy gender inequities and encourage cultural and racial pride. This brief addresses the genesis and legality of single-sex classrooms, the merits and critiques of single-sex education, and aims to avoid research or claims that are based on gender stereotypes. Research that both supports and opposes single-sex education is examined. Recommendations concerning single-sex education for educators and policymakers to consider are offered. (Contains 8 online resources.)