Ability grouping, defined as "the practice of organizing classroom groups in a graded school to put together children of a given age and grade who have most nearly the same standing on measures or judgments of learning achievement or capability," is considered in terms of its effect upon students' academic achievement and affective development. It is contended that grouping results in a trend toward improved achievement in superior groups and poorer achievement in the average or low groups. In addition, it tends to reinforce favorable self concepts in those assigned to high achievement groups and unfavorable self concepts in those assigned to low achievement groups. There seems to be a negative effect with regards to ethnic and socioeconomic separation. Misuses of standardized tests in grouping procedures are fully discussed. In view of the apparent inadequacies of present grouping practices, the following six alternative strategies are recommended: individualized instruction, heterogeneous grouping, stratified heterogeneous grouping, team teaching, student tutoring, and early childhood education. (Author/PR)