The role of transnational partnerships in contemporary global environmental discourse raises larger questions of the legitimacy, effectiveness and accountability of networked governance. This article advances a conceptual framework for evaluating the legitimacy of partnership networks. Furthermore, it examines, in particular, the multi-stakeholder partnerships for sustainable development announced at the World Summit on Sustainable Development in Johannesburg 2002. Partnership networks have been branded as a new form of global governance with the potential to bridge multilateral norms and local action by drawing on a diverse number of actors in civil society, government and business. Does the rise of global partnerships imply a re-location and diffusion of authority from government to public–private ‘implementation networks’? Recent evaluations of the Johannesburg partnerships suggest that they can gain from a clearer linkage to existing institutions and multilateral agreements, measurable targets and timetables, more effective leadership, improved accountability, systematic review, reporting and monitoring mechanisms. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.