AbstractExtensive studies of fusion economics have been performed in the last decade within the European Union and the United States. Over the same period major advances have been made in the physics and technology of fusion. This paper summarizes the prospects for fusion making an economically attractive contribution to the future energy mix. With modest physics optimization and anticipated near-term materials, the internal costs of fusion electricity would be about 50% more expensive than electricity from fossil fuels (not counting the costs of pollution abatement) and roughly comparable to renewables. Unlike renewables, fusion provides firm power. The use of advanced materials, technology and physics leads to an internal cost of fusion electricity approaching the internal cost from fission or fossil. Fusion has small external costs, along with wind, about an order of magnitude lower than fossil. Energy scenarios show that fusion could contribute significantly to large-scale electricity production during the second half of the century; the overall cost of fusion electricity is likely to be comparable with that from other environmentally responsible sources of electricity generation.