This paper reviews the economics literature on energy efficiency in India. The empirical literature has focused on four questions: How does energy efficiency in India compare with energy efficiency in other countries? What would be the energy savings (and cost savings) from adopting certain energy-efficient technologies? Why are these technologies being -- or not being -- adopted? What policies should be implemented to encourage their adoption? Most of the literature focuses on answers to the first two questions. Studies are needed that quantify factors affecting the rate of diffusion of energy-efficient technologies and rigorously evaluate reforms implemented by the Government of India, beginning in the 1990s, that could affect energy efficiency.