The OECD reported that the proportions of students enrolled in 'private schools' have remained stable since 2000. Drawing on the concepts of endogenous and exogenous privatisation, we question this statement, arguing that school privatisation can be disaggregated into four dimensions: private provision, restricted access, school competition and school autonomy. We operationalise these dimensions using indicators from the PISA school questionnaire. We explore changes cross-nationally between 2000 and 2018 in 35 educational systems, revealing increases in secondary school competition dynamics over time and some cases of substantial increases in autonomous school-level decision-making. We also provide an up-to-date landscape of school privatisation for 64 countries in 2018 and highlight the relevance of using a wide set of indicators to report the extent of privatisation, accounting for both endogenous and exogenous sides of the phenomenon. Finally, we discuss ways in which cross-national quantitative data collection on schools might be developed to produce a more appropriate quantification of privatisation.