text: Prevalence of childhood mental disorders in high income countries a systematic review and meta analysis to inform policymaking Mental disorders typically start in childhood and persist causing high individual and collective burdens To inform policymaking to address childrens mental health in high income countries we aimed to identify updated data on disorder prevalence We identified epidemiological studies reporting mental disorder prevalence in representative samples of children aged 18 years or younger including a range of disorders and ages and assessing impairment searching January 1990 through February 2021 We extracted associated service use data where studies assessed this We conducted meta analyses using a random effects logistic model using R metafor package Fourteen studies in 11 countries met inclusion criteria published from 2003 to 2020 with a pooled sample of 61 545 children aged 4 18 years including eight reporting service use All data were collected pre COVID 19 Overall prevalence of any childhood mental disorder was 12 7 95 CI 10 1 to 15 9 I sup 2 sup 99 1 Significant heterogeneity pertained to diagnostic measurement and study location Anxiety 5 2 attention deficit hyperactivity 3 7 oppositional defiant 3 3 substance use 2 3 conduct 1 3 and depressive 1 3 disorders were the most common Among children with mental disorders only 44 2 95 CI 37 6 to 50 9 received any services for these conditions An estimated one in eight children have mental disorders at any given time causing symptoms and impairment therefore requiring treatment Yet even in high income countries most children with mental disorders are not receiving services for these conditions We discuss the implications particularly the need to substantially increase public investments in effective interventions We also discuss the policy urgency given the emerging increases in childhood mental health problems since the onset of the COVID 19 pandemic PROSPERO CRD42020157262 