An occupational perspective of public health embraces a holistic view of the lifestyles of groups of people and how lifestyles influence health (Hocking, 2011). Adolescents, as a defined population group, are being positioned at the centre of global health practice, in the belief that investment in the well-being of young people yields a return for the whole of society into the future. Despite the fact that Ireland has the youngest population in Europe, little is known about the occupational nature and lifestyles of late adolescents in contemporary Ireland and how they spend their time. This cross-sectional study examined the time use of Irish late adolescents during weekdays and weekends, and how time use differed by two key determinants of health, gender and social class. A time diary survey was conducted with a representative sample of school-going adolescents. Seven hundred and thirty one young people participated (52% response rate; mean age boys 16.10 years; mean age girls 15.91 years). Non-parametric analyses of participation rates and time spent in activities across the day revealed the gendered nature of adolescent time use, particularly at weekends. Social class differences were less evident. This study contributes a unique occupational perspective on the time use of ‘well’ late adolescents in contemporary Ireland.