This chapter examines the structural dynamics of educational inequality, situating France within a half-century of international comparisons. We combine longitudinal and cross-sectional data for nearly 130 countries (1970–2020), enabling robust counterfactual analyses. Our findings reveal France’s persistent struggles: too many students fail to master basic skills, while socio-economic gaps remain among the widest in the OECD. By contrasting extremes—top versus bottom performers, privileged versus disadvantaged—we highlight the dual failure of low equity and limited performance. Ultimately, the chapter quantifies both the social and economic costs of inequality, underscoring the urgent need for more effective and fair education systems.