Abstract
International Large-Scale Assessments (ILSAs) have had a global influence on education in recent decades, and the Organisation for Economic Cooperation and Development (OECD) has played a leading role, most notably with the Programme for International Student Assessment (PISA). The organisation's latest ILSA is the International Early Learning and Child Well-being Study (IELS), a test of five-year-olds, which first reported in 2020. The OECD has portrayed IELS as significant, describing it as ‘a great example’ and the ‘future of assessment’. We locate IELS within the OECD's ILSA testing regime and its extensive critiques. Subsequently, through an analysis of IELS documentation, we explore its rationale and processes and then contrast these with its reported outcomes. We demonstrate that IELS has failed to deliver on its intentions and acutely manifests many of the problems that critics of ILSAs have identified. We argue that IELS has contributed to the waning interest in the OECD's testing regime and that other approaches to comparative research should be given greater attention.