Children and adolescents in low and middle income countries (LAMIC) constitute 35-50% of the population. Although the population in many such countries is predominantly rural, rapid urbanisation and social change is under way, with an increase in urban poverty and unemployment, which are risk factors for poor child and adolescent mental health (CAMH). There is a vast gap between CAMH needs (as measured through burden of disease estimates) and the availability of CAMH resources. The role of CAMH promotion and prevention can thus not be overestimated. However, the evidence base for affordable and effective interventions for promotion and prevention in LAMIC is limited. In this review, we briefly review the public health importance of CAM disorders in LAMIC and the specific issues related to risk and protective factors for these disorders. We describe a number of potential strategies for CAMH promotion which focus on building capacity in children and adolescents, in parents and families, in the school and health systems, and in the wider community, including structural interventions. Building capacity in CAMH must also focus on the detection and treatment of disorders for which the evidence base is somewhat stronger, and on wider public health strategies for prevention and promotion. In particular, capacity needs to be built across the health system, with particular foci on low-cost, universally available and accessible resources, and on empowerment of families and children. We also consider the role of formal teaching and training programmes, and the role for specialists in CAMH promotion.