Planning for elections, calculating the denominator in disease incidence rates, assessing natural disaster impacts, measuring demand for services—underlying all of these activities and many more is the need for ongoing subnational scale data on population sizes and characteristics. While it is often taken for granted that fine-grained, robust, consistent and recent data on populations are readily available in high income settings, obtaining consistent, comparable and spatially-detailed demographic data for resource poor regions can be a challenge. Census data can be incomplete, unreliable or outdated, while registration systems are often weak or lacking completely, and limited funds, conflicts and poor access to many areas make the collection of new data difficult. These features present substantial obstacles to strategic planning for disease elimination, vaccine delivery, reliable health metrics, health system planning and outbreak control. Moreover, with increasing population mobility, the demographic distributions of countries are changing rapidly, with human mobility patterns influencing disease transmission dynamics and elimination efforts. Professor Tatem will provide an overview of the work of WorldPop (www.worldpop.org) and Flowminder (www.flowminder.org) in developing and implementing geospatial methods for integrating census, survey, satellite and cellphone data to strengthen the demographic evidence base in low and middle income settings. He will show how collaborations around geospatial demographic data with governments, UN agencies and others across a range of low income settings are strengthening national statistics, improving health intervention delivery, feeding into disaster response efforts and supporting disease elimination initiatives.