Temporal analyses of social movement mobilization provide insight into how repression shapes social movement tactics and in turn, how social movements affect state response. We use the case of environmental dissent in Communist Czechoslovakia to unpack this interplay. The regime quelled activism and was grossly negligent in environmental matters, fomenting an underground environmental movement. Our data included archival documents, historical accounts, and in‐depth interviews. Findings indicate the importance of political context in examining state tactics. We highlight how dissidents can test the boundaries of state tolerance to expose vulnerabilities of the state as well as political opportunities for activism.