Energy-efficient technologies offer considerable promise for reducing the costs and environmental damages associated with energy use. However, these technologies appear not to be used by consumers and businesses to the degree that would apparently be justified based on their private financial net benefits. Broader societal benefits of energy efficiency, including to the environment, add further to this gap if they are not reflected in individual decisions. The initiative at Duke and Harvard Universities with which this group is associated will advance understanding of this "energy efficiency gap" and the diverse factors that affect the adoption of energy-efficient equipment and practices. The initiative focuses on differences between predicted and observed adoption of these technologies, and its findings will inform future research and policy.