Philanthropy’s role in advancing sustainable development attracts a lot of attention. This report calls into question long-held assumptions about the volume, nature and potential of foundations’ engagement in developing countries, and the role they can play to support the SDGs. It presents ground-breaking data and analysis that capture previously non-existent global and comparable quantitative and qualitative data on how foundations support development. The report examines philanthropic resource flows for development purposes, as well as foundations’ priorities, practices and partnering behaviours. It presents fresh perspectives and action-oriented recommendations to optimise philanthropy’s role in support of sustainable development. This report offers practical insights for government policy makers and decision makers in civil society organisations, social enterprises and foundations. It results from close co-operation between the OECD Development Centre’s Network of Foundations Working for Development (netFWD) and the OECD Development Co-operation Directorate.