Introduction: Educational achievement gaps matter not only for equity but also for later skill formation and labour market outcomes. Understanding how these gaps evolve during secondary school is therefore important for both educational and economic policy.

Goal: This paper explores the factors associated with achievement gaps and their evolution among secondary school students in Greece. It primarily focuses on gender, ethnic origin and father’s occupation and asks whether their associations with performance differ across students’ cohorts, subjects and school years.

Methodology: The analysis uses administrative longitudinal data for 2014-2025, covering five complete distinct cohorts of students. Achievement gaps are proxied by differences in standardised school grades in the Greek language and mathematics. The empirical strategy combines both descriptive and regression analysis, utilizing the longitudinal nature of the data, i.e. following the same student throughout secondary education.

Main findings: The results show that students’ performance is associated with gender, ethnic origin and father’s occupation, but the relation varies across years and subjects. Gender gaps in favour of female students are wider in the Greek language and widest in the first year of upper secondary education. Native students outperform non-native students in both examined subjects, although the gap narrows as students advance to upper secondary education. Father’s occupation is also strongly related to achievement, with higher status occupations associated with better outcomes; in both subjects, the effect of higher status occupations on achievement gaps is even stronger than the gender effect.

Conclusions/Contribution: The paper contributes longitudinal evidence on the changing structure of educational inequalities in Greece proxied by achievement gaps. Findings suggest that achievement gaps in secondary education are persistent but dynamic, evolving as students advance through the school system. Gender emerges as the strongest correlate of performance differences, implying that targeted interventions in upper secondary education may be particularly valuable. Ethnic origin remains relevant, although its effect is smaller than that of gender. Father’s occupation also matters, highlighting the role of family environment in shaping student achievement outside the formal school system.

JEL: I24