The Lancet Psychiatry Commission on youth mental health.

Competing Interests: Declaration of interests PDM is a founding director, patron, and former founding board member of headspace. He is the executive director of Orygen, Australia's National Centre of Excellence in Youth Mental Health and lead agency for five headspace centres across northwest Melbourne. He is a past President of the International Association for Youth Mental Health, and a past President of the IEPA; Early Intervention in Mental Health and of the Schizophrenia International Research Society. S-JB has provided paid expert witness work for UK charities and legal organisations. She is the author of two books related to the brain, education, and learning, for which she receives royalties. She gives talks in schools in the state and private sector, at education conferences, for education organisations, and for other public, private, and third sector organisations (some talks are remunerated). She is a member of the Rethinking Assessment group, the Steering Committee of the Cambridge Centre of Science Policy, the Technical Advisory Group for the UK Government Department of Education's Education and Outcomes Panel-C Study, the Singapore Government National Research Foundation Scientific Advisory Board, and the Singapore Government Human Potential Scientific Advisory Board. She was a member of the Times Education Commission (2021–22). IBH has received honoraria for consultancy and educational activities from Janssen Cilag. He was a member of the Clinical Advisory Group for the evaluation of the Better Access to Psychiatrists, Psychologists and General Practitioners through the Medicare Benefits Schedule initiative, and is a member of Mental Health Reform Advisory Committee (Department of Health). He is the Chief Scientific Advisor to and a 3·2% equity shareholder in InnoWell, which aims to transform mental health services through the use of innovative technologies. FAEA has received honoraria for consultancy from Grand Challenges Canada and is a past member of the World Economic Forum's Global Future Council on Mental Health. AMC is a director of headspace, Australia's National Youth Mental Health Foundation, and the National Education Alliance for Borderline Personality Disorder. AD is the Academic Secretary for the Royal College of Psychiatrists’ Faculty of Child and Adolescent Psychiatry, a research advisory group member of the UK National Society for the Prevention of Cruelty to Children, a member of the UK Trauma Council, and an evidence panel member of the Early Intervention Foundation. TF's research group receives funding for consultancy to Place2Be, a third sector organisation that provides mental health training, support, and interventions to schools across the UK. JH is executive director of Youth Wellness Hubs Ontario and receives funding from Graham Boeckh Foundation and other donors through the Centre for Addiction and Mental Health Foundation. AJ is a trustee of the Samaritans and MQ. She has received fees for lecturing from the Scottish Association of Mental Health. She is an advisory board member of Our Future Health, UK. FK-L's work is the subject of publishing contracts with multiple companies in the EU, Magellan, Cobalt Therapeutics in the USA, and the National Health Service in the UK. Although she has received no remuneration to date, she might receive royalties in the future. She is a non-executive director of Orygen. CK is the founder of Wida, a digital mental health platform. He has received consulting fees from the UN Children's Fund. He has received grants from MQ: Transforming Mental Health in the UK, the Royal Academy of Engineering in the UK, the National Institutes of Health in the USA, the Medical Research Council in the UK, and Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul in Brazil. DR is a Chief Scientific Advisor to headspace, Australia's National Youth Mental Health Foundation. JT receives book royalties from Simon and Schuster, legal consulting fees from Bergman and Little and the Attorney General's office of the State of Tennessee, and honoraria for speaking engagements. EK is the immediate past President of the IEPA: Early Intervention in Mental Health, and during the period of the Commission was the President elect and President. All other authors declare no competing interests.