We provide a measure of equality of educational opportunity in 54 countries, estimated as the effect of family background on student performance in two international TIMSS tests. Using cross-country variation in education policies and its interaction with family background at the student level, we then estimate how equality is related to organizational features of the education system. We find that equality of opportunity is positively related to late tracking into different school types and to longer pre-school education. Pre-school enrollment has an inverted U-shaped relationship with equality. Equality is negatively related to private school financing, but positively to private provision.