This policy brief provides an overview of the findings from a national cost-benefit analysis on mental health and psychosocial support (MHPSS) interventions among children and adolescents aged five years and above in education settings in Thailand. These focused interventions aim to promote the mental health and well-being of children and adolescents, prevent and respond to mental health conditions, and thereby promote learning and educational outcomes. Building on global and national research conducted by UNICEF and partners, the brief identifies the economic costs of mental health conditions to families, communities, and Thailand as a whole due to the adverse impact these conditions have on school completion and education outcomes. The impact of failing to address the mental health and psychosocial support needs of 5-19 year-old children and adolescents would result in the equivalent of a national US$816 million (28,600 million baht) loss of potential lifetime earnings. Furthermore, it describes the substantial economic benefits of addressing these unmet mental health needs through the implementation of evidence-based MHPSS interventions in education settings. The cost-benefit analysis provides complementary insights to enrich evidence-based policy decisions in education, with an enhanced focus on children's well-being and learning.