Despite much research on age and attitudes, it remains unclear whether age reflects accumulated life experience or conditions prevailing during an individual's formative years – that is, a life-cycle effect or a cohort effect. In respect to attitudes towards the European Union (EU), the issue is particularly important. Although many analyses indicate a correlation between age and support, the relationship has not been adequately theorised and extant analyses have generated contradictory results. In this article, theoretical expectations for both life-cycle and cohort effects on support for the EU are developed and tested using a cross random effects model. This not only identifies the nature of an age-support relationship, but also highlights substantial generational differences in attitudes towards European integration and explains the inconsistencies in extant empirical analyses.