The Alaska School Effectiveness Project produced several reports in a series of reviews of research literature on such topics as instructional grouping: ability grouping. Using an ERIC search and conventional library methods, the question raised was "Do students in the aggregate perform equally well academically and have comparable attitude and self concepts whether they receive instruction in homogeneous or heterogeneous groups?" The overall conclusion was that high-ability children should receive instruction with one another, and that lower-ability children should receive instruction with higher-ability children. Given the difficulty of such an arrangement, it is recommended that: (1) schools which currently practice heterogeneous grouping and are experiencing satisfactory achievement levels and student morale are advised not to change (provided higher-ability children receive enrichment activities); (2) educators should be made aware of the very negative effects of homogeneous ability grouping on the cognitive and affective development of children classified as low-ability; (3) teachers should be made aware of instructional materials and methods which can be effective with heterogeneous classes; and (4) where the decision has been made to institute or maintain homogeneous grouping, steps should be taken to mitigate negative effects of this grouping format. The document includes item decision displays, a 24 citation bibliography, and individual item reports on the citations. (BRR)