Age as a determinant of political beliefs can be conceived as capturing one of two broad processes: ageing effects, wherein ageing or changes over the life-cycle produce differences between age groups and cohort effects, wherein generations are ‘socialised’ and retain distinctive features over time. Thus far, comparative analysis of the effects of age and cohort have only been performed for beliefs on European integration. Analysis of left-right and libertarian-authoritarian beliefs have been restricted to national analyses primarily in the UK. This paper therefore fills the gap created by this apparent lack by performing an exploratory comparative age-period-cohort analysis for left-right and libertarian-authoritarian beliefs in Western Europe. It finds that age-related processes matter considerably more for authoritarian-libertarian beliefs. These results imply that as these beliefs become more salient, so too will age differences in political preferences – and therefore perhaps political behaviour.