This second of two volumes on issues surrounding oil and gas examines a succession of fundamental changes in the European energy economy during the last 40 years. Examined are the reasons why imported oil replaced indigenous coal as the primary energy source in the early post–World War II period; the discovery and exploitation of the North Sea basin’s hydrocarbons resources; and the evolution of the continent’s natural gas markets from the early 1960s, when it accounted for less than two percent of total energy used, to the current contribution of more than 25 percent and an expected eventual share of 35 percent of Europe’s energy supply. These powerful and complex dynamics of Europe’s energy sector are then put in the context of the broader political and economic structures and policies that have emerged over the last four decades.