This study examined the effects of peer-tutoring training on elementary school student communication and collaboration skills when used in conjunction with cooperative learning. Within six classes (grades 2–6) in an inner-city school, cooperative learning pairs were randomly assigned to two groups (control and training). Multivariate analyses of variance (MANOVA) of quantitative data from a systematic observation instrument used over an entire year showed that, in general, the training group surpassed the control group in both communication and collaborative skills. Students in grades 2–3 showed substantially more improvement than students in grades 4–6; also, students with average or below-average reading levels required more time to acquire these skills than did above-average students. The qualitative data further substantiated these findings while revealing a large variation among teachers in implementing cooperative learning.