New partnerships between governments, private companies, and nongovernmental organizations (NGOs) are reshaping global environmental governance. In particular, there has been a rise of voluntary sustainability standards in an attempt to manage social and environmental impacts of global supply chains. We analyze the large spectrum of interactions between private, public, and civil society actors around voluntary sustainability standards, primarily for tropical agriculture and forestry. This review uncovers a policy ecosystem dominated by a proliferation of standards that complement, substitute, or compete against each other, with coordination mechanisms beginning to arise. Contrary to widely held views, interactions between governments, NGOs, and private companies surrounding the adoption of sustainable practices are not generally antagonistic, and public and private environmental governance regimes rarely operate independently. The influence of these interactions on the effectiveness of sustainability standards needs more attention. Better understanding how private regulations interact with the policy ecosystem will help design more effective interventions.