This article discusses private environmental governance at the global level. It is widely acknowledged that corporations play an increasing role in global environmental politics, not only as lobbyists in international negotiations or agents of implementation, but also as actors creating private institutional arrangements that perform environmental governance functions. The rise of such private forms of global governance raises a number of questions for the study of global environmental politics: How does private governance interact with state-centric governance? In what ways are the roles/capacities of states and nonstate actors affected by private governance? Does the rise of private governance signify a shift in the ideological underpinnings of global environmental governance? This article explores these questions, seeking a better understanding of the significance of private environmental governance for International Relations.