Personal networks and media are viewed as the most influential channels for social movement mobilization. Interestingly, social media play both roles, but whether they achieve the same effect of mobilization is unknown. Regarding personal networks, research has shown that being asked by acquaintances through personal contact (i.e., face-to-face and telephone) is the key determinant of social movement participation. This study used a Web survey to investigate the relationship between the channel of mobilization and participation in the context of political consumerism in Taiwan. The results showed that being asked through personal contact was still the most effective predictor of social movement participation. The results showed that mass media had no effects. Social media also failed to influence social movement participation. Although personal networks in social media are large, few members actually mobilize others to participate in social movements because they fear public disclosure of their personal political stance, and most users have weak ties. These factors lead to the ineffectiveness of appealing through personal networks on social media.