Social unrest often begins suddenly and spreads quickly. What is the information that drives its diffusion? How is this information transmitted? And who responds to this information? We present a general framework that emphasizes three aspects of the diffusion process: the networks through which information travels, whether information about repression affects participation, and the role of organizers. We use this framework to derive empirical hypotheses that we test in the context of the English Swing riots of 1830-31. This was the foundational case in the study of unrest in social history, and our identification strategy relies on spatiotemporal variation particular to this historical period. We find that diffusion was significant and that information about the riots traveled through personal and trade networks, but not through transport or mass media networks. This information was not about repression; and local organizers played an important role in the diffusion of the riots.