AbstractNational research assessments play a role in providing accountability—to funders, government and civil society—for the activities of largely autonomous research systems. Increasingly, an element of such assessments is the assessment of societal impact. In this article, I review the development of impact assessment, with a focus on the UK’s Research Excellence Framework, and consider implications and challenges for the future. Notwithstanding these challenges, I further argue that the assessment of societal impact needs to become a more central aspect of research evaluation. This article is published as part of a collection on the future of research assessment.