The second edition of the AA-HA! guidance amplifies AA-HA! messages and advances the case for investing in adolescent health and well-being in important ways.

• It integrates learnings from the application of the first edition of the AA-HA! guidance.
• It provides the latest data on the determinants of health, mortality, morbidity and well-being and highlights the recent consensus on core indicators for adolescent health and well-being.
• It builds on significant political and scientific advances since 2017 and integrates the concept of well-being into the programming process. Thus, the second edition takes the important step of moving from a largely health-centric perspective to a more holistic understanding of adolescent well-being, including its implication for programming.
• It incorporates learnings from the COVID-19 pandemic.