Peer influence on students has been of interest to sociologists for some time. But most studies of elementary classroom interaction have focused primarily on teacher-student interaction. A study of peer influence on other group members was designed to explain why students assigned to low ability groups became inattentive more frequently than students assigned to high ability groups. Sixteen videotapes of reading classes in a first grade classroom with 23 students were analyzed. The students were assigned to four ability groups: high, medium-high, medium-low, and low. Results indicated that peer influence was one process by which ability group assignment influenced student attentiveness. Often one student's behavior affected several peers simultaneously. Verbal behavior was more distracting than nonverbal behavior. Most cases of peer influence on attentiveness occurred in the medium-low reading group, indicating that boredom may have been an influencing factor. The finding that students influenced peers so frequently during the teacher-directed lessons suggests that peers are likely to be important influences on students' behavior during most classroom lessons. (JAC)