This paper examines the earthquake monitoring and prediction program, called “collective monitoring, collective defense,” in communist China during the Cultural Revolution, a period of political upheavals and natural disasters. Guided by their scientific and political ideas, the Chinese developed approaches to earthquake monitoring and prediction that emphasized mass participation, everyday knowledge, and observations of macro-seismic phenomena. The paper explains the ideas, practices, and epistemology of the program within the political context of the Cultural Revolution. It also suggests possibilities for comparative analysis of science, state, and natural disasters. The paper redefines the concept of “citizen science” and argues that the concept provides a useful comparative perspective on the intimate relationship between science and the macropolitics of modern state and society.