In countries such as Italy, Germany, Hungary, Luxembourg and Turkey there are large differences between schools, linked to the schools’ and students’ socio-economic backgrounds. The magnitude of the differences in performance associated with the socio-economic composition of the school is striking, especially in Austria, Belgium, Czech Republic, Germany, Israel, Japan5, and the Netherlands. One student attends an advantaged school, where most of this student’s peers come from families that are more affluent6. The other student attends a more socio-economically disadvantaged school.7 The analysis indicates that the first student would be expected to show, on average across the OECD countries, a 32 score point higher reading performance than the second student, and this difference would be expected to exceed 50 score points in several countries.