This study examined the effects of classroom in degree for ability (the degree to which peer nominations as academically capable show high consensus and focus on a relatively few number of children in a classroom) on first grade children's peer acceptance, teacher-rated classroom engagement, and self-perceived cognitive competence. Participants were 291 children located in 84 classrooms. Participating in sociometric interviews were 937 classmates. Consistent with social comparison theory, classroom in degree moderated the associations between children's achievement and classroom engagement and peer liking. Children with lower ability, relative to their classmates, were less accepted by peers and less engaged in classrooms in which students' perceptions of classmates' abilities converged on a relatively few number of students than in classrooms in which peers' perceptions were more dispersed. High in degree was associated with lower self-perceived cognitive competence regardless of ability level.