The purpose of the present study was to assess the social adaptation of mainstreamed mildly retarded children, comparing them to a matched sample of regular education students. Results indicated that mildly retarded children were quite rejected by their peers, and, compared to nonretarded classmates, they reported significantly more dissatisfaction and anxiety about their peer relations. With respect to behavioral style, there were no group differences in peer- or teacher-reported aggressiveness or disruptiveness. However, retarded children were perceived as more shy and avoidant, as less cooperative, and as less likely to exhibit leadership skills. Further analysis of the behavioral assessment data, via cluster analysis, revealed 2 subtypes of rejected retarded children: an internalizing group perceived as displaying high levels of shy/avoidant behavior and an externalizing group perceived as high in aggressive and/or disruptive behavior. In addition, the internalizing group reported higher social anxiety than did the externalizing group. Implications for school-based intervention research with mildly retarded children are discussed.