Whereas the division of labour between the state and the private sector regarding the costs of education constitutes a major bone of contention in public debates and varies widely between OECD countries, it has hitherto hardly been scrutinized empirically. This paper identifies its most important political, social and cultural determinants in 28 OECD member states. The major findings are that the publicness of education funding is lower where Conservative and Christian centre parties govern and where Protestantism is more widespread, whereas the influence of trade unions and, perhaps surprisingly, Liberal parties increases the ratio of public to private education expenditure. Further, but smaller effects are yielded by federalism and fiscal decentralization, public subsidies for educational purposes, public indebtedness and intra-firm vocational training systems in the former and by mandatory private social expenditure in the latter direction.