This report studies the effect of increasing the number of children with a migrant background in a classroom on natives test scores in reading and mathematics. It uses data on primary school children from two large international surveys that allow to produce estimates for most EU member states. The report does not find strong evidence for either negative or positive spillover effects from non-natives to natives’ children. The lack of any sizeable effect is independent of the starting level of concentration of students with a migrant background in the classroom: for both classes with few and classes with, relatively, many pupils with a migrant background, the estimated effect of increasing the number of students with a migrant background is close to null. The report also explores whether an urban/rural gap exists in the ability of schools to integrate students with a migrant background finding no difference.