The question of ability grouping in education has achieved prominence, especially in recent years. Much of the emphasis placed on grouping students according to ability rather than chronological age is a product of modern times and progressive education. Although not accepted by all educators, there is a definite movement toward such a procedure in public schools today. It is held by the advocates of ability grouping that students will benefit more in a situation where they proceed at a rate prescribed by their ability rather than a hypothetical average or norm. Several well-controlled studies (3, 33, 44) have shown that in situations where students are grouped homogeneously according to respective ability there is an increase in achievement. All of these studies have compared performance and achievement under both systems of grouping and have showed that the homogeneously grouped students benefit more than students in a social promotion situation. The stand taken by the advocates of ability grouping is therefore expressed in terms of achievement and academic advantages. This, for the most part, comprises the reason for preference over traditional social promotion. The argument against ability grouping is based primarily on social injustice to the student. Although this argument finds little support in terms of well-controlled research and empirical evidence, several articles (5, 17, 54) illustrate why many educators oppose ability grouping on the basis of social injustice. There is little disagreement as to the merits of such a procedure in terms of student achievement, however. The concern lies rather in pupil adjustment in situations where he learns at a rate prescribed by his ability among only those possessing similar ability. Theoretically, this places students in all of the ability levels in restricted environments which in turn limits social interaction. If students do not learn to adjust to diverse social situations in the school and during these critical years of development, where and when will they learn? This is a major question raised by those who oppose ability grouping. The possibility that ability grouping might not only inhibit adjustment in social situations, but also have a negative effect upon the self concept of students is also characteristic of this argument. An example of this would be the slow learner who is placed in a group which proceeds at a slower rate than that of others his age. This student recognizes that his performance and ability are inferior to those students in other groups. It is possible that in such a situation the student might acquire feelings of inferiority which may persist and develop into more serious emotional disorders later. This, the opposition to ability grouping would maintain, is of major concern.