A relatively new class of roof coatings has been shown to save significant amounts of cooling energy. Cool roof coatings reflect away the bulk of the sun’s energy, allowing the roof surface to stay cooler and transferring less heat to the building underneath. Demonstration projects have shown these coatings can save between 20 and 70% of the cooling energy used in a building. These coatings also have the potential to save money, reduce air pollution, and lessen the need for reroofmg. There are still technical and industrial challenges in the way of the widespread adoption of these coatings as the roofing standard. This paper first reviews the radiative properties of roof materials, then summarizes the results from numerous projects which demonstrate the effectiveness of these coatings at saving cooling energy. The challenges of accurately modeling and predicting the energy savings of cool coatings are discussed. The non-energy benefits of cool coatings are described. Barriers to the implementation of cool coatings are enumerated and the challenges facing researchers and the coating industry are considered.