Turnout inequality is on the rise in most advanced democracies. Even though education is a key determinant of individual voter turnout, its macro-level expansion has not led to an increase and equalisation of turnout, but the opposite. This paper addresses this puzzle by examining the role of educational expansion –tertiary education in particular– in widening the turnout gap in post-industrial democracies. Drawing on the relative education model, I argue that status anxiety emerges for those without tertiary education in societies where average education attainment keeps increasing. This is not a story of relative deprivation, which can mobilise political participation. Instead, status anxiety diminishes internal political efficacy, demobilising non-tertiary-educated citizens and exacerbating turnout inequality. Using a database comprising 15 Western democracies over 60 years (1964-2024), I show that turnout inequality has increased over time due to a sharper decline in turnout among citizens without higher education. Multilevel interactive models reveal that rising average education levels strengthen the association between individual education and voter turnout, indicating a widening turnout gap. Moreover, I confirm the expectation that non-tertiary-educated individuals increasingly withdraw from voting as the proportion of tertiary-educated citizens grows. Potential compositional effects arising from self-selection into education are addressed through additional robustness checks. This paper advances not only the study of turnout inequality but also the broader field of electoral participation, emphasising the importance of considering structural factors and their consequences for social hierarchies when explaining longitudinal trends in political participation.