LAUSR

OBJECTIVE Recent studies suggest deteriorating youth mental health. The current UK policy emphasises the role of schools for mental health promotion and prevention, but little data exist on what aspects of schools explain pupils' mental health. We explored school-level influences on the mental health of young people in a large school-based sample from the UK. METHOD We analyzed baseline data from a large cluster randomized controlled trial (ISRCTN 86619085) collected between 2016‒2018 from mainstream UK secondary schools selected to be representative in relation to their quality rating, size, deprivation, mixed or single-sex pupil population and country. Participants were pupils in their first or second year of secondary school. We assessed whether school-level factors were associated with pupil mental health. RESULTS 26,885 pupils (response rate=90%), aged 11‒14 years, 55% of which were female, attending 85 UK schools, were included. Schools accounted for 2.4% (95% CI=2.0‒2.8; p<0.0001) of the variation in psychopathology, 1.6% (95% CI=1.2‒2.1; p<0.0001) of depression and 1.4% (95% CI=1.0‒1.7; p<0.0001) of well-being. Schools in urban locations, with a higher percentage of free school meals and of White British, were associated with poorer pupil mental health. A more positive school climate was associated with better mental health. CONCLUSION School-level variables, primarily related to contextual factors, characteristics of their pupil population, and school climate explain a small but significant amount of variability in young people's mental health. This might be used to identify schools that are in need of more resources to support young people's mental health.