Book excerpt: This report aims to support impact evaluation in the energy sector by assessing what has been produced against what might be possible. It reviews 85 impact evaluations of energy interventions in developing countries, summarizes findings on outcomes, identifies evidence gaps, and proposes ways forward. A majority of studies has so far focused on rural electrification and improved cookstoves, while most investments are in power generation and transmission. After considering the body of evidence available, directions and approaches are proposed for future impact evaluations to best contribute new evidence regarding the sector.