This paper provides a review of the macro-level evidence on the importance of electricity for economic development. We find that electricity access and use are strongly correlated with economic development, as theory suggests. Despite a large empirical literature, however, there are few methodologically strong studies that establish causal effects of either electricity use or electricity infrastructure on economic growth. The micro-level literature provides more convincing evidence of causal effects, although these appear not to be uniform in all locations. We present a number of country case studies that are suggestive of electrification playing an important role in broad-based development progress. The paper also identifies potential avenues for future research. High-quality macro-level evidence on the economic effects of electricity access and reliability would help policy-makers and aid agencies make decisions regarding investment priorities.