Environmental governance regimes concerned with the management of biological life have encouraged not only new forms of expertise, but also political activism and struggle. One such regime, the international Cartagena Protocol on Biosafety (Biosafety Protocol), a subagreement of the Convention on Biological Diversity (CBD), seeks to monitor the potential risks of releasing living modified organisms, such as transgenic seeds, into the environment. Drawing on market-oriented visions of environmental conservation and risk management, the Biosafety Protocol is closely tied to the development of new bioeconomies and the ascent of neoliberal principles globally. NGOs and environmentalists have played prominent roles in the Biosafety Protocol by occupying spaces designated for civil society participation, raising the question of how activists both disrupt and sustain the neoliberal logics embedded in new regimes of environmental governance. I explore this question through ethnographic research in Costa Rica among activists, biosafety officials, and private biosafety auditors, where activists have engaged biosafety as part of a campaign against transgenic seeds. Working with limited resources and a genuine concern to manage the risks of agricultural biotechnology, officials draw on strategies that position both the market and civil society as key mechanisms of biosafety monitoring. Despite opposing transgenics and the concept of biosafety, activists participate in the government biosafety commission as civil society representatives and informally monitor local fields. Officials have labeled activists “biovigilantes,” viewing them as parallel to private biosafety auditors who subsidize the lack of state capacity in biosafety. Recent research on civil society and governance suggests that discourses of participation have depoliticizing impacts, encouraging specific forms of self-conduct that reinforce a dominant order of things. Illustrating how activists occupy and negotiate civil society and biosafety expertise, I argue by contrast that their engagement with biosafety is uneven and contradictory, revealing an unsettled struggle, rather than some prevailing governmental logic.