Regional electricity systems, or power pools, can reduce the cost of providing electricity and improve system reliability through co-ordinated use of energy resources. Realizing these benefits requires a strong political will to co-operate combined with careful market design supported by technical, economic and institutional analysis. In this chapter, we present some of the unique motivations for power pools in Africa, describe the current status of pooling arrangements on the continent, study in detail the regulation of transmission in the Southern African Power Pool (SAPP) and identify some improvements to the present rules. Our approach combines mathematical modelling of the SAPP system using linear programming with analysis of regional institutions and their role in promoting efficient investments as well as efficient market behaviour. We have investigated several market-design questions, such as how to identify, implement and allocate costs for necessary regional transmission investments. Our regulatory proposals developed for the SAPP could be feasible options for other regional systems in Africa that face similar institutional and technical challenges in developing regional infrastructure.