The past two decades witnessed the emergence of a new range of transnational social movements, networks, and organizations seeking to promote a more just and equitable global order. With this broadening and deepening of cross-border citizen action, however, troubling questions have arisen about their rights of representation and accountability—the internal hierarchies of voice and access within transnational civil society are being highlighted. The rise of transnational grassroots movements, with strong constituency base and sophisticated advocacy capability at both local and global levels, is an important phenomenon in this context. These movements are formed and led by poor and marginalized groups, and defy the stereotype of grassroots movements being narrowly focused on local issues. They embody both a challenge and an opportunity for democratizing, legitimizing, and strengthening the role of transnational civil society in global policy.