Recent literature on the effectiveness of donor programmes points to the importance of understanding the political context within which reforms are taking place. The characteristics of the power sector make reform intensely political in almost all countries and donor projects have sometimes failed because of an inability to navigate the local politics of reform. This article reviews what is known about how donors have taken politics into account in designing and implementing power sector reform programmes in sub-Saharan Africa. It illustrates the challenges which donors have faced with reference to a case study of donor attempts to support power sector reform in Tanzania. The article draws on documentary evidence from major donors as well as a set of qualitative interviews with experienced project supervisors to provide a set of lessons for donors about how to incorporate political context into the design and implementation of power sector projects.