Ability grouping is supposedly undesirable because it leads to deficits in academic self-concept and academic achievement. However, it appears to be justifiable for its improvement of teaching and learning in schools, perhaps more so in a collectivist culture. In view of the paucity of data examining the controversy in Hong Kong, the authors collected data from 2,720 junior high school students with a random sampling procedure and obtained teachers' reports about the students' subsequent academic achievement, ability grouping, and the ability level of the class. The authors maintained students' past academic achievement as a control variable in predicting their subsequent academic achievement and self-concepts. Results revealed no significant detrimental effect caused by the ability-grouped class and the ability level of the ability-grouped class. Rather, students in classes that were more homogeneous according to past academic achievement tended to have significantly higher subsequent academic achievement and self-esteem. Results revealed no variation attributable to each student's gender and IQ in the effects of ability grouping. [Copyright of Journal of Educational Research is the property of Routledge. Full article may be available at the publisher's website: http://dx.doi.org/10.1080/00220670309598813 ]
