Corporations react to the regulatory drivers instituted by government and to a lesser extent the private initiatives of non-governmental organisations (NGOs). In contrast to the adversarial model, firms and NGOs may form partnerships for the satisfaction of mutual objectives such as influencing the development of public policy or reforming international legal regimes. This article considers one such partnership – the Energy and Biodiversity Initiative – within the regulatory context of conserving biological diversity and protecting heritage-listed or environmentally-sensitive areas. Four firms and five NGOs jointly formulated operational guidelines for integrating biodiversity considerations into upstream oil and gas development including where commercial projects are located within or adjacent to protected areas. They each contributed biodiversity data, knowledge of environmental management systems, project management skills and information concerning best commercial practice. As demonstrated at the recent Fifth World Parks Congress in South Africa, their efforts were reflected in the adoption of intergovernmental guidelines which envisage further partnerships between governments, firms, civil society and indigenous communities. Illustrative of constructive feedback loops between the public and private spheres within the international lawmaking process, firms and NGOs have secured influential roles in applying and reforming the protected area management system of the World Conservation Union. The EBI is assessed for the lessons it offers for prospective corporate-NGO partnerships, its success in establishing dialogue and trust between the business and conservation communities on controversial questions such as mining in protected areas and as a possible model for private protected area governance.