Mental health problems in schools are a concern and various initiatives have been developed to address these. Interventions can be universal (covering a whole school) or targeted (addressing those with specific needs). Any new intervention should be evaluated, and this should include an assessment of cost-effectiveness. Evidence to date suggests that while gains from universal schemes may be modest, they can still be cost-effective given the extent of their reach. However, targeted interventions can address key health inequalities which should also be an objective of an economic evaluation. Studies that have examined the longer term impact of both universal and targeted approaches have demonstrated that both can represent good values for money, and it is likely that a blended or tiered approach is appropriate.