Black Lives Matter, Occupy Wall Street, the global justice/anti-globalization movement, the radical environmental movement of the 1990s, and other organizations have moved away from traditional hierarchical models of leadership within their movements in favor of more horizontal, “leader-full” structures or network models. More horizontal or network models have been used even when a group of people is engaged in what might ordinarily be considered “service” work, like disaster recovery and feeding the hungry. Relatedly, organizers of mass mobilizations may engage the support of lawyers even before these actions crystallize into a movement or formally structured organization—as informal governance structures exist in the planning and execution of these mobilizations. One example is the Ferguson Legal Defense Network, which formed under the direction of trusted lawyer contacts amidst the mass mobilizations in Ferguson in the aftermath of the police killing of Michael Brown Jr. This short contribution examines some of these non-traditional, social movement-based lawyer-client relationships, evaluates the accompanying professional responsibility challenges, and offers preliminary approaches. These challenges—though not insurmountable—require thought and a foundational understanding of the goals and methods of social movement organizations.