While the radical right is relatively successful on social media, only a fraction of its supporters become activists offline. Why do some individuals become offline activists in radical right organizations, while others prefer to limit their support to online spaces? Following an inductive analysis of interviews with activists and supporters of a radical right organization, this study points to the importance of going beyond classical explanations for activism by focusing on the impact of, and relationship between, group identification and stigma for mobilization. It shows that activists who identify with the organization and consider it stigmatized are motivated to participate in protest actions to speak out in front of this perceived injustice. By contrast, supporters who question the organization’s legitimacy in the face of stigma engage with the organization on social media and are motivated by a desire to keep a low profile and to avoid being openly associated with stigmatized actors.