Mental health difficulties affect 1 in 10 children and adolescents, and up to half of adult cases begin during the school years. The individual and societal impacts of such difficulties are huge, and include poorer quality of life, lost economic productivity, destabilisation of communities, and high rates of health, education and social care service utilisation. Using early intervention and prevention in schools as a central component of a co-ordinated response to this emergent public health crisis makes good sense. Schools play a central role in the lives of children and their families, and their reach is unparalleled. It has been argued that truly comprehensive and effective mental health promotion in schools requires a universal screenin...