89 children and their mothers participated in a study examining the association between attachment and peer social competence. During the summer following kindergarten, quality of attachment was assessed from reunion episodes following a 1-hour separation. In the fall, measures of sociometric status, peer behavior nominations, and peer liking ratings were collected. Teachers completed liking ratings and ratings of behavior problems and competence. Consistent with longitudinal studies of infant attachment and peer relations, insecurely attached boys were less well liked by peers and teachers, were perceived as more aggressive by classmates, and were rated by teachers as less competent and as having more behavior problems than were their secure counterparts. No such associations emerged for girls. Possible explanations for unanticipated differences in the pattern of results for boys and girls are discussed.