BackgroundA public mental health lens is increasingly required to better understand the complex and multifactorial influences of interpersonal, community and institutional systems on the mental health of children and adolescents.MethodsThis research review (1) provides an overview of public mental health and proposes a new interactional schema that can guide research and practice, (2) summarises recent evidence on public mental health interventions for children and adolescents, (3) highlights current challenges for this population that might benefit from additional attention and (4) discusses methodological and conceptual hurdles and proposes potential solutions.ResultsIn our evidence review, a broad range of universal, selective and indicated interventions with a variety of targets, mechanisms and settings were identified, some of which (most notably parenting programmes and various school‐based interventions) have demonstrated small‐to‐modest positive effects. Few, however, have achieved sustained mental health improvements.ConclusionsThere is an opportunity to re‐think how public mental health interventions are designed, evaluated and implemented. Deliberate design, encompassing careful consideration of the aims and population‐level impacts of interventions, complemented by measurement that embraces complexity through more in‐depth characterisation, or ‘phenotyping’, of interpersonal and environmental elements is needed. Opportunities to improve child and adolescent mental health outcomes are gaining unprecedented momentum. Innovative new methodology, heightened public awareness, institutional interest and supportive funding can enable enhanced study of public mental health that does not shy away from complexity.