Since the 1973 Oil Crisis, the European Union (the European Community in the 1970s) has become one of the actors in the international arena to have faced the obstacles in respect to the energy issue and has paid more careful consideration to the issue of energy security. The main reason for this is that the European Union (EU) is unable to meet its own energy needs, and is becoming increasingly dependent on oil and natural gas resources. Following the energy crises in the 2000s, European member states have argued that energy is no longer a question of economics, but rather a matter of politics. Debates on the development of the European energy policies have become dominated by a discourse of insecurity relating to the questions of energy dependence and the relations with energy suppliers, repeating the discussions from the energy crises of the 1970s. In such a context, the primary objective of this book is to give a comprehensive analysis of the securitization process of European energy policies based on the particular security speech acts of European actors between the energy crises of the 1970s and those of the 2000s. Through doing so, I compare these speech acts to see how securitization played different roles during both periods and thus analyze the policy initiatives which led to a policy fragmentation, on the one hand, and Europeanization of the energy policies, on the other hand. This book essentially argues that in contrast to the 1970s' crises, after the 2000s' energy crises, the effects of securitization were positive, which accelerated both the Common Energy Policy (CEP) efforts and the Europeanization of energy policies within the EU.