Provides a framework to guide practitioners in designing sustainable and pro-poor energy delivery systems which are based on market approaches but also take into account the social principles of development and the reality in which development projects operate. The framework includes the analysis of the market chain of each energy system, and an examination of its enabling environment as well as the supporting services that, due to the challenging conditions of the development context, might be required. The messages conveyed are illustrated by a series of relevant case studies of on-grid, mini-grid and off-grid delivery services, highlighting their shortcomings as well as their successes, and giving key recommendations.