The Guidelines on promotive and preventive mental health interventions for adolescents - Helping Adolescents thrive (HAT), provide evidence-informed recommendations on psychosocial interventions to promote mental health, prevent mental disorders, and reduce self-harm and other risk behaviours among adolescents. The HAT Guidelines aims to inform policy development, service planning and the strengthening of health and education systems, and facilitate mainstreaming of adolescent mental health promotion and prevention strategies across sectors and delivery platforms.