The population dynamics presented in this paper have serious implications for South Sudan’s human development and political stability. Using census data and UN estimates, this briefing paper highlights South Sudan’s recent demographic patterns and trends, starting in 2008 into 2050. The projections presented are based on an exponential growth regime, and the analysis seeks to provide key insights for the aid community to stimulate their thinking on the nature and level of support likely to be needed in the country over the next 30 years. The analysis explores the implications of demographic changes on South Sudan’s economy, social welfare, and human security. Finally, the brief provides both donors and domestic practitioners with actionable recommendations for present and future programming or planning.