The persistence of social inequities in education – the fact that children of wealthy and highly educated parents tend to do better in school than children from less privileged families – is often seen as a difficult-to-reverse feature of education systems. Yet countries across the world share the goal of minimising any adverse impact of students’ socio-economic status on their performance in school. PISA shows that, rather than assuming that inequality of opportunity is set in stone, school systems can become more equitable over a relatively short time.