Useful site: The Global Impact Investing Network

Extract from site:

"The GIIN supports collaboration, develops industry infrastructure, and undertakes research and advocacy to foster a coherent impact investing industry. The GIIN's programmatic agenda is rooted in the challenges investors face. It serves as a forum for identifying and addressing the systemic barriers that hinder the impact investing industry's efficiency and effectiveness. 

The GIIN works to increase dramatically the level and effectiveness of capital that is supporting market-based solutions to social and environmental problems. Our goal is to help foster a coherent impact investing industry that channels investment capital efficiently to accelerate the development of solutions to pressing social and environmental problems. Impact investing can be a powerful complement to philanthropy and government efforts to address many issues, including relief for suffering communities, eradication of disease, stabilization of climate change, provision of basic social services such as housing and sanitation, and development of a green revolution in Africa. "