AbstractAs one alternative source of energy for the future, fusion power will be required to demonstrate that it can be a safe, clean and economically attractive option in an increasingly diverse and competitive energy marketplace. Top-level requirements have been developed and used to guide the development of fusion power concepts, most recently, the ARIES-RS conceptual power plant design based upon the tokamak operating in the reversed shear MHD mode. This design is shown to have the potential to meet the necessary requirements. We review the present status of this and other power plant designs, identify the key fusion R and D issues in a variety of technological areas, and point to the need for a coordinated, and international, R and D effort to achieve the ultimate goal of a commercially desirable fusion system.