There is sufficient evidence indicating the efficacy of interventions in reducing risk factors, increasing protective factors, preventing psychiatric symptoms and new cases of mental disorders. Macro-policy interventions to improve nutrition, housing and education or to reduce economic insecurity have proven to reduce mental health problems. Specific interventions to increase resilience in children and adolescents through parenting and early interventions, and programmes for children at risk for mental disorders such as those who have a mentally ill parent or have suffered parental loss or family disruption, have also shown to increase mental well-being and decrease depressive symptoms and the onset of depressive disorders. Interventions for the adult population, from macro-policy strategies, such as taxation of alcohol products or workplace legislation, to individual support for those with signs of a mental disorder, can reduce mental health problems and associated social and economic burdens. Exercise, social support or community participation have also shown to improve mental health of older populations. Public mental health will benefit from continuing building the evidence base through combining different evaluation methods across low, middle and high income countries. The translation of evidence into policy and practice calls for action at the international, national and local level, including building capacity, advocacy, mainstreaming mental health into public health and other policies and securing infrastructures and sustainability. Mental health professionals have an important role to play in improving the evidence on prevention and promotion in mental health, in engaging relevant stakeholders for developing programmes, and as professional care providers in their practice.