Instructional and Institutional Effects of Ability Grouping

This paper attempts to uncover the mechanisms through which stratification in schools differentiates student achievement. Two types of mechanisms are considered: (1) technical conditions of differentially allocated instruction, and (2) institutional processes operating through symbolically defined categories. Using data from twelve first-grade classrooms, I isolated the instructional effects and found that they are both large and stable. Institutional processes account at most for a small grouping effect, which occurs early in the year but fades as the year progresses.