Homogeneous grouping of mathematics students, the practice of grouping students of similar ability or achievement, is most prevalent at the high school level, often occurs at the middle and junior high school levels in schools that offer algebra, and occurs at the elementary school level as part of general groupings. This digest summarizes research results on the long-term effects of this practice on mathematics education. Effects are reported in three categories: (1) opportunity to learn mathematics; (2) mathematics achievement; and (3) tracking practices. Results indicate inequities in access to strong mathematics programs, well-qualified teachers, and classroom opportunities for low-track students enrolled in schools that practice homogenous grouping. Studies indicate that homogeneous grouping, especially at the high school level, generally fails to increase learning and seems to widen gaps between students deemed to be more or less able. Research on tracking practices involving the effects on minority and female students indicates that these students are often placed in lower tracks, particularly at the secondary school level, a troubling result considering the low representation of female and minority students in science and mathematics areas. Contains 18 references. (MDH)