This paper presents a research summary on ability grouping and tracking, and makes recommendations to school practitioners on successful alternative strategies to educate children from diverse backgrounds. The research reveals little evidence that ability grouping improves academic achievement, while overwhelming evidence exists that it retards the academic progress of students in low- and middle-ability groupings. The effect of ability grouping is to widen the achievement and knowledge gap between groups of students, due to differing instructional practices and teacher expectations. Ability grouping serves as a form of segregation by race, socioeconomic background, gender, language, and special education status. Furthermore, this segregation brings into question whether discriminatory procedures are used to determine ability levels. It is unclear whether ability grouping eases the task of teaching for all ability level classes, but the evidence clearly indicates that it is an ineffective means of addressing individual differences. The research indicates that schools should implement alternatives to the use of ability grouping and tracking practices. Recommendations are presented for the following topics: (1) assessment and planning; (2) grouping of students; (3) curriculum and instruction; (4) staff development; and (5) student and family support. Nine examples of schools that have made the transition from homogeneous to heterogeneous grouping are included. A brief list of terms and their definitions is included. Also appended are 59 footnotes and a 10-item bibliography. (JS)