Polycentric governance networks are on the rise in global energy and climate governance, but we know surprisingly little about their empirical performance. This paper analyzes the performance of four such transnational energy and climate governance networks. In the realm of sustainable energy, our cases are the Renewable Energy and Energy Efficiency Partnership (REEEP) and the Global Alliance for Clean Cookstoves (GACC). In the climate sphere, we examine the effectiveness of the Green Climate Fund (GCF) and the Clinton Climate Initiative (CCI). Using principles from governance and public administration about the effectiveness of institutions, we examine the extent to which four networks have contributed to improving governance outcomes in the spheres of climate and sustainable energy. Our evaluation focuses on the clarity of purpose, funding, institutional formality, efficacy, and level of resilience of these networks. Some differences notwithstanding, we find that the transnational governance networks generally fail to meet the criteria about what constitutes an effective institution. The paper concludes with a reflection on what could be done to enhance the performance of these governance networks.