Youth peer groups hold many different types of norms, including norms supporting aggressive behavior. Challenging or standing up to such aggressive norms can be difficult for children and adolescents, given the pressures to conform to groups. In the current study, the relationship between individual judgments and expectations of the judgments of a peer group about the acceptability of challenging aggressive group norms was investigated. The sample included 9–10 and 13–14 year-olds ( N  = 292, 52.4 % female). Participants evaluated groups with norms condoning physical and relational aggression. Participants were more supportive of challenges to relational aggression than challenges to physical aggression. Additionally, age-related differences were found, with younger children perceiving challenges to group norms as more feasible than did adolescents. Participants individually rated challenging aggressive norms as okay, but thought that groups would be much less supportive of such challenges. The results also documented the influence of gender stereotypes about aggressive behavior on children’s and adolescents’ evaluations.