Extreme cases in demography are important challenges for researchers, and the still important heterogeneity of European societies is a blessing for scholars interested in studying the importance of cultural and institutional factors. In the transition to adulthood the "latest-late" pattern of Southern Europe cohabits with its opposite "earliest-early" pattern of the Nordic countries. In this paper, I discuss multifaceted approaches to the explanation of why becoming an "adult" in Europe appears so diverse. I use secondary data analyses and present cross-country correlations: welfare state and institutional arrangements, historical and deeply rooted cultural differences, as well as economic and policy factors, and ideational change. Moreover, micro-level determinants play different roles in different societies.