In China, urban middle class mobilization against potential pollution risk has become increasingly common. This article examines this phenomenon through a detailed case study of a 2009 anti-waste incinerator campaign in the Panyu District of Guangzhou, which culminated in a sizeable public protest and government U-turn. This episode revealed tension between the narrow, state-centered regulatory model fixated on end-of-pipe pollution control, and a much broader decentered approach advocated -and practiced -by project opponents, which incorporated public consultation and much greater emphasis on upstream waste reduction and sorting. In the process, the Panyu campaign progressed beyond a case of "regulation by escalation," whereby beneficial regulations are belatedly enforced following populist pressure. Instead, it transformed into an open dialogue between a plurality of actors, including citizens, journalists, experts, and officials, about what regulation should constitute and who should determine acceptable levels of risk. By focusing on the processes through which regulatory issues emerged and changed during the Panyu campaign, this article highlights the regulatory dynamism of environmental mobilization in a context of regulatory uncertainty, and campaigns against "locally unwanted land uses" more broadly.