This Article demonstrates that a new revolving door is emerging between environmental-advocacy groups and the private sector. Since the birth of the modern regulatory state, scholars have raised concerns that the revolving door between corporations and government agencies could induce government officials to pursue corporate interests rather than the public interest. The legal and political-science literatures have identified several benefits that may arise from the revolving door, but the thrust of the scholarship to date has emphasized the potential harms. Using several data sources, we demonstrate that as the private sector has begun to play an increasing role in environmental governance in recent years, a new revolving door has emerged between environmental-advocacy groups and corporations, institutional investment firms, and private equity firms. We demonstrate that this new revolving door is surprisingly common, and we examine the implications for the future of public and private environmental governance. Although this new revolving door creates new risks, we argue that it may turn on its head the central concern about the revolving door: The movement of environmental advocates into corporate management positions may play the role of greening corporate behavior and may accelerate the development of private environmental initiatives. We focus on the movement of employees in the environmental area—a new green revolving door—but we suggest that this new revolving door also may be emerging in labor, health and safety, and other regulatory areas.