The COVID-19 pandemic has led to school closures across the UK and many countries across the world, with the majority of pupils in these systems out of school, though supported and taught in various ways. There has been great concern that school closures will lead to slower rates of learning or learning loss, and there is a risk that the negative impact will be worse for pupils who are economically disadvantaged. This rapid evidence assessment aimed to examine the potential impact of school closures on the attainment gap, based on a systematic search of existing literature. Eleven studies were identified that provided quantitative evidence about the impact of school closures on attainment gaps. A subset of nine studies provided comparable estimates that could be synthesised.