This study explores how social investors in Asia measure the social impact of their investments. It contains two main sections. The first section provides an overview of the literature on social impact measurement, with a specific focus on impact assessment for social enterprises. The second section explores how investors and foundations measure and report on their social impact. Relying on publicly disclosed data, like corporate websites, evaluation reports and annual reports, I analysed the standards and practices of 77 investors and foundations. The organisations in this sample all make decisions about the allocation of funds — whether these are grants, equity or loans — to social-purpose organisations. The organisations are either grant-making foundations or impact investors that invest in social enterprises, and are operating in Asia.