Despite the increasingly authoritarian atmosphere in Russia and China, mass protests in both countries are pervasive, including protest motivated by environmental grievances. Existing scholarship often focuses on the sources, spread, or volume of mass mobilization, but few examine how civil society actors themselves evaluate the tactic. How does the state respond to environmentally-motivated mass mobilization? In light of the state’s response, how have activists altered their approach to mass mobilization over time? Using case studies and interviews, I find that Russian and Chinese environmental groups approach mass mobilization in distinct ways. Over time, Russian activists have increasingly turned to mass tactics, including coordinated regional protest. Meanwhile, Chinese ENGOs have reduced their formal involvement in such campaigns, limiting visible horizontal linkages between environmental groups. These approaches are shaped by the different historical legacies of mass mobilization in either country, which also shape state perceptions of the threat posed by environmental activism.