Abstract
This article deals with the recent change of the global regime controlling ocean dumping of low-level radioactive waste. Why did this regime, which originally permitted ocean dumping of low-level radioactive waste, undergo a regime change that resulted in this activity being outlawed? It is concluded that the actions of a global environmental non-governmental organization (ENGO) were decisive in the regime change process, independent of state interests or epistemic communities. Four primary roles for ENGOs in environmental regimes are suggested — mobilizing international public opinion, transnational coalition building, monitoring of states' environmental commitments and advocating precaution and protection of the environment. It is concluded that regime studies should pay more attention to ENGOs and interaction between ENGOs, states and epistemic communities.