Population Services International is a non-profit organization based in Washington, D.C., that harnesses the vitality of the private sector to address the health problems of low-income and vulnerable populations in more than 60 developing countries. With programs in malaria, reproductive health, child survival, HIV and tuberculosis, PSI promotes products, services and healthy behavior that enable low-income and vulnerable people to lead healthier lives. Products and services are sold at subsidized prices rather than given away in order to motivate commercial sector involvement. PSI is the leading non-profit social marketing organization in the world.