Since its 2005 General Conference, UNESCO has supported the recognition, validation and accreditation (RVA) of the outcomes of nonformal and informal learning for youth and adults and acknowledged the importance of RVA in the development of lifelong learning systems. Globally, the scale of need is enormous. There are significant challenges in integrating the recognition, validation and accreditation of the outcomes of non-formal and informal learning at the basic education level into existing RVA systems and in enabling young people and adults without basic education to complete such processes successfully. This report summarizes the research and policy dialogue of an international expert group invited by UNESCO to three meetings in 2016. It focuses on three themes – principles, policy and practice – and provides examples of how the issue is being approached across the world. It offers 12 conclusions, based on the evidence considered by the expert group, and proposes a number of key messages for stakeholders in Member States, including policy-makers and the research community.