In this chapter, students will learn about the various meanings of ‘energy security’ and consider why it has attracted so much attention from both policy makers and the general public. In particular, international concern over the future availability of non-renewable energy supplies is ascribed to doubts about the ability of energy producers to keep pace with rising world demand and the vulnerability of global supply lines to terrorism, piracy and war. The task of satisfying consuming states’ requirements for energy is being further challenged by a shift in the centre of gravity of world energy consumption from West to East, a growing reliance on remote and hard-to-reach sources of supply, and rising concern over climate change. Various strategies for enhancing energy security are also considered.