Over the past 250 years, energy transitions have occurred repeatedly—the rise of coal in the nineteenth century, the explosion of oil in the twentieth century, the nuclear utopianism of the 1950s and 1960s. These transitions have been as revolutionary as any political or economic upheaval, and they required changes in infrastructure and behavior. Yet new energies never wholly replace old ones. This volume historicizes energy production and consumption while demonstrating how energy use has reshaped everything from social life and economic organization to political governance. It foregrounds the importance of energy for big historical questions about capitalism, democracy, inequality, the environment, and identity, and it argues that energy systems themselves merit attention as key agents of historical change. Given the urgency of climate change, and the central position that energy plays in causing and potentially solving global warming, this volume engages history as a discipline in the debate over what may be most monumental energy transition of all time: the shift away from fossil fuels.