The purpose is to feed into the international discussions of environmental financial mechanisms such as for forestry and mercury by examining the performance of the GEF. We discuss performance against effectiveness and legitimacy and focus on institutional set-up and key actors as explanatory factors. Methodologically, we use document and literature analysis and interviews with key actors in organizations, state representatives and NGOs. The dominant position of the USA and the World Bank has probably contributed to the bias towards a northern environmental agenda and emphasis on effectiveness and climate change projects. The GEF has somewhat predictably diverted the flow of international money from the poorest countries to more rapidly developing countries. Still, despite turf battles between the organizations involved, the broad organisational and thematic composition of the GEF has comparative advantages. This enhances the score on legitimacy especially for biodiversity projects, although they receive less overall funding. The GEF may be seen as an indication of how, regardless of choosing established or new institutions, basic power structures and interests of dominating parties will be largely decisive for what can be achieved in global environmental governance.