A meta-analytic review of group comparison design studies evaluating peer-assisted learning (PAL) interventions with elementary school students produced positive effect sizes (ESs) indicating increases in achievement. PAL interventions were most effective with younger, urban, low-income, and minority students. Interventions that used interdependent reward contingencies, ipsative evaluation procedures, and provided students with more autonomy had higher ESs. (Contains 162 references, 7 tables, and 1 appendix.) (GCP)