Adolescence is a critical stage in the life course, shaping the chances of a productive and fulfilling future for girls, boys and the societies they live in. Investments in adolescents can improve their lives today, tomorrow as they mature into adults, and can have positive effects on the next generation of children. The Maternal, Newborn, Child and Adolescent Health (MNCAH) team in the Data and Analytics Section at UNICEF-HQ takes a comprehensive approach to adolescent health and well-being. We have expanded our areas of focus from reproductive and maternal health issues to include mental health and well-being, injuries, and risk factors for non-communicable diseases and other poor health outcomes (e.g., lack of physical activity, tobacco, alcohol and drug use). One area of innovative work that we are leading on is a methodological approach to measure adolescent mental health at the population level.