We currently report three studies investigating group members' expressions of dissatisfaction and discontent with the behaviour and attitudes of their in-group members. Our analysis examines the context in which group members will deviate from actual group member behaviour. We argue that highly identifying group members will challenge fellow group member behaviour when that group member behaviour is perceived to violate injunctive group norms. Further, we predicted that high identifiers would still challenge such group member behaviour even if that behaviour were conducted by a majority of group members. Thus, high identifiers were predicted to express descriptively deviant opinions when the behaviour of other members contravenes injunctive group norms. In Studies 1 and 2, group-level self-definition served as a moderator in the relationship between the expression of discontent and perceived injunctive norm violation; in Study 3, group-level self-investment served as this moderator. The findings supported our predictions. This support was particularly strong when a majority of group members violated group norms. Implications for the analysis of the relationship between social identification and deviance are discussed.