Ability grouping refers to the organizing of elementary and secondary students into classrooms or courses for instruction according to actual or purported ability. This entry briefly reviews the history of ability grouping in American public education and how the law has treated challenges to this practice in various types of settings, primarily when such grouping results in significant levels of segregation or discrimination based on race. Legal constraints on ability grouping based on language, disability, and gender are also identified. The entry concludes with a review of policy features that may help predict the legal vulnerability of ability grouping practices and of factors that school officials may find important to consider as they contemplate grouping students to foster excellence without sacrificing equity in the current ...