The OECD Global Action “Promoting Social and Solidarity Economy Ecosystems”, funded by the European Union, through its work stream on social impact measurement, endeavours to: 1) explore current social impact measurement practices among social and solidarity economy organisations; 2) identify the methodologies best suited to capture the social benefits of the social and solidarity economy; and 3) understand what policy initiatives can be used to foster a social impact measurement culture and practice in the social and solidarity economy.After discussing the origins and drivers of social impact measurement, this paper examines existing methodologies developed at the local, national and international level and finally reviews how these are being implemented in the social and solidarity economy. It takes stock of the policy mapping exercise conducted by the OECD, which draws on responses to an online survey and on the stakeholder consultations conducted in Brazil, Canada, India, Korea, Mexico and the United States.