This paper looks at the relationship between migration between developing countries - or countries of the global ‘South' - and processes of human development. The paper offers a critical analysis of the concept of South-South migration and draws attention to four fundamental problems. The paper then gives a broad overview of the changing patterns of migration in developing regions, with a particular focus on mobility within the African continent. It outlines some of the economic, social and political drivers of migration within poor regions, noting that these are also drivers of migration in the rest of the world. It also highlights the role of the state in influencing people's movements and the outcomes of migration. The paper highlights the distinctive contribution that migration within developing regions makes to human development in terms of income, human capital and broader processes of social and political change. The paper concludes that the analysis of migration in poorer regions of the world and its relationship with human development requires much more data than is currently available.