The Social Cognitive Mapping procedure was used to identify peer social groups in 26 fifth-grade classrooms from six elementary schools in a northeastern urban school district. Four group structural features were examined: size, the number of subcliques, cohesion, and salience hierarchy. Ethnic diversity index was calculated for each group. An ethnically diverse sample of 318 fifth-grade students participated in the study, and 80 peer groups were included in the analyses. No gender difference was found in group size, cohesion, salience hierarchy, or ethnic diversity. Reliable gender differences were found in the number of subcliques within a group and in the individual child's involvement in any subclique, with higher levels for girls than for boys. However, the overall prevalence of subcliques was low. The findings highlighted strong similarities across the two genders and contradicted the predictions made by traditional sexual-selection theory. Group features varied by status, indicating significant within-gender variations. (Contains 4 tables.)