Following earlier reforms in the power sectors of industrialized countries and emerging markets (e.g. Chile), developing countries were encouraged to unbundle their electricity industries and to introduce competition and private sector participation. This paper highlights the developments that led to how power sector reform came to be defined as a standard model and theoretical framework in its ownright, and how the model was used prescriptively in many developing countries. However, we also show that, after more than 15 years of reform efforts, this new industry model has not fully taken root in most developing countries. Finally, we identify and characterize the emergence of new hybrid power markets, which pose fresh performance and investment challenges.