This study investigates how child and adolescent time use differs across Finland, Italy, Spain and the UK, four countries capturing clearly distinct policy and cultural regimes. Studying children’s time use cross-nationally provides new understandings of the micro-macro drivers of children’s daily activities with critical implications for their personal development, future lifestyles and identity formation. The study uses rich time-diary data from 2008-2015 for a pooled sample of children aged 10-17 from Finland, Italy, Spain and the United Kingdom (N = 6,556), applying multiple linear regression models addressing (i) between-country and (ii) within-country variations. Findings are consistent with the Cross-Cultural Hypothesis by revealing that Finnish children spend the lowest time with parents and the highest time alone and with ‘others’, after accounting for multiple factors. In Italy and Spain, children’s time with parents is the highest, and time alone and with others clearly lowest. The UK lies somewhere in between the Scandinavian and Mediterranean models. In ‘family-oriented’ Italy and Spain, children spend more time eating (i.e., having dinners), while in more ‘individualistic’ Finland and UK screen-based time is highest (i.e. mobile phone use). The Structural Opportunities Hypothesis receives little support. Parental education generally leads to more time in educational activities in all four countries, while maternal employment generally weakly predicts children’s time use across activities and national contexts. Overall, the strong cross-national differences observed in child and adolescent time use do not seem driven by simple structural or socioeconomic opportunity contexts, but rather by cross-cultural differences in values around family relations and individuals’ daily routines.