This study examined the effects of peer tutoring on children's social interactions and compared social interaction behaviors between children who are English-language learners (ELL) and children who are primary English speakers (PES). Single-subject withdrawal design (ABA) was applied in this study and classwide peer tutoring was used as the independent variable. Seven ELL and seven PES from two early primary-grade classrooms were selected as the participants. Participants' ages ranged from six to eight years old. Results of this study showed that classwide peer tutoring was effective for both ELL and PES. The data also indicated that the intervention (classwide peer tutoring) was relatively more effective for the ELL group than for the PES group. In both groups, children were engaged in very few negative behaviors. (Contains 4 tables and 4 figures.)