"Delayed participation" in higher education (HE) is an increasingly important feature of modern HE systems in many countries. Despite this, surprisingly little empirical research has been undertaken seeking to better understand levels of delayed adult participation in HE across Europe. The present article responds to this gap by analysing country-level data on delayed adult participation in HE across 15 European countries and by modelling associations between participation levels and a range of theoretically derived economic, social, demographic and systemic factors. The findings suggest that there is considerably more cross-national variation in levels of adult delayed participation and that prevalent typologies of HE, such as Trow's, fail to give recognition to the importance of delayed participation. The modelling work finds that social and demographic factors exhibit relatively strong associations with delayed participation in HE. This questions the pre-eminence of economic factors within much of the academic literature, policy discourse and policy activity.