This study used 2009-2015 time-diary data to examine gender differences in daily activities among children and adolescents aged 10-17 in Finland, Spain and the UK (N = 3517). In all three countries, boys were significantly more involved in screen-based activities and exercising and girls in domestic work, non-screen educational activities and personal care. Gender differences in socializing time were only significant in the UK, with girls socializing more than boys. Gender gaps within countries were largest in domestic work (UK: 60%; Finland: 58%; Spain: 48%) and exercising (UK: 57%; Finland: 36%; Spain: 27%), followed by educational time (UK: 35%; Finland: 34%; Spain: 18%) and screen-based activities (UK: 31%; Finland: 16%; Spain: 16%), and lower in personal care (UK: 27%; Finland: 21%; Spain: 14%) and socializing (UK; 21%; Finland: 13%; Spain: 6%). Two-way country-gender interactions in children's activities were statistically significant when comparing Spain and the UK on screen-based activities, socializing, and personal care, with larger gender gaps in the UK than in Spain. By contrast, gender differences in child time use between Finland and either Spain or UK were not statistically significant. The complex role of national contexts and life-course stages in shaping gendered time-use patterns is discussed.