The health and well-being of adolescents: responding to their priorities.

Adolescents aged 10-19 years represent the largest cohort in human history and a critical global resource-yet realizing their potential requires deliberate, sustained investment in their health and well-being. This editorial introduces a six-article supplement in Health Policy and Planning addressing key priorities for adolescent health and well-being policy and programming, with particular attention to young people's own perspectives and evidence from low- and middle-income countries. The supplement opens with findings from the 'What Young People Want Survey', drawing on responses from over 1.5 million young people across 89 countries. Results reveal that adolescents' priorities span multiple domains-especially learning and employability, safety and supportive environments, and health and nutrition-underscoring the necessity of multi-sectoral approaches. Three articles address financing. Together, they demonstrate that integrated health-education interventions can yield returns of at least 11 dollars per dollar invested and that scaling up treatment for adolescent depression and anxiety produces benefit-cost ratios of 15.4 and 13.9 in Colombia and South Africa, respectively-while cautioning that investments must be designed with an explicit equity focus to avoid deepening existing inequalities. Another article presents new World Health Organization and Partnership for Maternal Newborn and Child Health guidance for monitoring adolescent health and well-being holistically across the five domains of the UN conceptual framework, supported by an Excel-based data tool that maximizes use of existing data. The supplement concludes with an early assessment of commitments made at the 2023 Global Forum for Adolescents across four countries, finding that progress is hindered by fragmented systems, funding gaps, and insufficient disaggregated data. The evidence presented in this supplement makes clear that improving adolescent health and well-being is neither aspirational nor unaffordable-it is an investment with compelling returns. Realizing those returns demands that adolescents' voices shape policy and that progress is rigorously monitored.