The present research investigated the role that threat to social image and self-conscious emotions play in reaction to deviance. In three studies, participants were invited to imagine themselves in a situation in which they were bystanders of a deviant behavior. We manipulated the threat to the in-group's social image through the deviant group membership (Study 1), the visibility of the deviant behavior to a third party (Study 2), and the stereotype salience of the deviant behavior (Study 3). Social image concerns, emotional reactions, and intention of sanctioning the deviant were measured. The results revealed that the situations in which the threat to the social image of the group was high provoked the greater intentions to sanction the deviant. Moreover, intentions were accounted for by the more intense shame and embarrassment (but not guilt) reported by the participants when faced with a group-threatening situation. The findings indicate that reactions to deviance are highly dependent on the damage caused to the group's social image and on self-conscious emotions. Copyright © 2011 John Wiley & Sons, Ltd.