Development Media International (DMI) delivers mass media campaigns to promote health in developing countries. It is the first organisation to scientifically prove that mass media can change life-saving behaviours. It recently completed a 5-year, £7m randomised controlled trial in West Africa which showed that 35% more children were taken for treatment for malaria, diarrhoea and pneumonia. Child mortality was reduced by 9.7% as a result. DMI is ranked as one of the most cost-effective non-profit organisations in the world by GiveWell.