This is Volume IV of a four volume set reporting on research on Africa funded by the Gates Foundation. Volume I is focused on conditions that make growth possible; Volume II deals with human development; and Volume III discusses ways in which modernization has come to sub-Saharan Africa, including banking, mobile phones, and dimensions of the export sector. Volume IV examines whether recent African growth rates will prove sustainable. This volume offers three different ways to address this general question. First, five of our research teams look at the details of African agriculture, ranging from its overall prospects to the specific institutional arrangements in two countries. As in our other volumes, the chapters here set a high standard in terms of putting together high quality data and analyzing it using appropriate statistical and econometric technique. Second, one team looked carefully at barriers to trade within West Africa – what keeps markets segmented and prevents trade from developing? Can these obstacles be overcome in the foreseeable future? Four teams look at particular country case studies to understand growth and development and also pay considerable attention to episodes of poor economic performance. Researchers participating in this project were encouraged to combine careful NBER-type empirical analysis with investigations of specific country experiences. In terms of in-depth country analysis, this volume includes material on Cape Verde, Ghana, Kenya, Mali, Mauritius, Mozambique, Niger, Nigeria, Sierra Leone, and Uganda.