The authors examine indicator research over three periods and discuss shifts in policy usage over time. The study compares influential actors that reflect discursive shifts in how, and for what purpose, indicators were used: (1) Jullien de Paris, (2) faculty at Teachers College at Columbia University in the early-twentieth century (notably Paul Monroe and Isaac Kandel) and (3) UNESCO Institute for Statistics’ contribution to the debate on the 2030 Sustainable Development Goals (SDGs) indicators. Arguably, these periods reflect the broader agenda and usage of indicators: modernization/nation-building (Jullien), colonization/ development (Monroe and Kandel) and standardization/globalization (SDGs). In this view, indicators make systems comparable, despite their differences: educational systems are not comparable per se, they are made comparable through standardized measurement. Jullien crucially shaped empirical research through uniform questions that enable description, analysis and comparison educational systems’ key features. Recently, policy analysts and researchers have referred to those standardised questions as indicators.