This chapter examines whether WTO provisions on trade in goods and services address adequately members’ concerns relating to energy security. This issue is discussed from the perspective of trade in sustainable energy, in particular natural gas, which is the least carbon-intensive resource among fossil fuels, biofuels, and renewable electricity. Energy security is a complex, multi-faceted issue, which must be analyzed from the perspective of the interests of major stakeholders in energy trade: an energy-importing State, an energy-exporting State, and, where applicable, a transit State. For each of these stakeholders, energy security has a different meaning. For energy importers, energy security can be defined as availability, affordability and sustainability of energy supply. For energy exporters, energy security means the ability to control own natural resources and the security of energy demand. Transit States often have regulatory concerns regarding the transit of energy through their territories, having a direct impact on the energy security of other members. In addition, practical challenges associated with energy security may vary depending on the energy source in question. The chapter identifies a number of issues affecting members’ energy security that are not adequately addressed by WTO law, and suggests ways to improve the WTO legal framework through the negotiations on a new comprehensive agreement on energy in the WTO.