The South American Physical Activity and Sedentary Behavior Network (SAPASEN) was designed to provide transnational empirical evidence about physical activity and sedentary behavior in South America, which represents 12% of world's surface and 6% of the global population. This sub-continent presents singular culture and distribution of diseases as well as lifestyle behaviors, especially due to an accelerated urbanization process, recent aging of population and considerable levels of poverty. This initiative aims to form a representative body of researchers and policy makers from all South America countries to establish priorities, targets and actions in short, medium and long-term.