For the first time, this book brings together three controversial topics: homogeneous grouping of students within classrooms by ability or achievement criteria, tracking of students into courses of study by the same criteria, and retention of students in their present grade so that they repeat a year’s work instead of being promoted. The editors solicited syntheses of research on these topics from outstanding scholars with a variety of views. Initial versions of the chapters were discussed at a national invitational conference sponsored by the Laboratory for Student Success, the Mid-Atlantic Regional Educational Laboratory, at Temple University Center for Research in Human Development and Education (CRHDE) through a contract with the former Office of Educational Research and Improvement (OERI), now the Institute of Education Sciences (IES) of the U.S. Department of Education. At the conference, the chapter authors benefited from discussions with one another, other scholars, policymakers, educators, and parents. Their recommendations are reported in the last chapter.