In order to achieve a low-carbon world, it is essential to make the use of energy far more efficient and to introduce a very significant amount of renewable or otherwise carbon-free generation. Yet, these steps alone will not decarbonize electricity. Each scenario in the DDPP reports envisions dramatic reductions in the use of fossil fuels to generate electricity. Fossil-fired generation, utilizing coal and natural gas, provides a lion’s share of the gigawatt hours serving end-use customers, and shows no sign of abating. History does not support the assumption that cleaner technologies will push out the dirtier ones. What are needed are affirmative actions designed to phase out the use of fossil fuels to generate electricity. Affirmative steps come in various forms. They start with planning—recognizing current patterns of fossil fuel use and charting a different course. Action can include some combination of specific state and federal prohibitions on the use of fossil fuels by all electric service providers; limits on GHG emissions; closure or divestment of government-owned fossil-fueled generators; and the implementation of policies that have a direct or indirect effect on the cost of power from carbon-emitting sources. The chapter expands on the nature of the challenge and describes the range of solutions in greater detail. The chapter has two appendices. The first, written by Stephen Herzenberg, recommends social policies to accelerate a fossil fuel phaseout. The second, written by Michael Gerrard, recommends ways of addressing stranded assets.