As educators know well, there are many barriers to learning that originate outside of school, such as those that arise from socio-economic disadvantage. In many education systems, the concentration of disadvantaged students in certain schools poses an additional challenge. Yet it is also true that schools with effective learning environments and high-quality resources can compensate, at least partially, for larger social inequalities. If school systems are to level the playing field, so that all children, regardless of their family background, are offered the best possible education, then the types of practices and resources that are related to better student performance need to be used in every school, not just in advantaged schools.