This chapter proposes a critical analysis of Transnational Organized Crime (TOC) as a security concept. It proposes an ontological reflection on the concept of security, by underlining how the understanding of this concept has evolved since the Cold War. The chapter discusses the securitization of TOC in the context of European Union (EU) to show how discourses are produced and how definitions emerge. The end of the Cold War thus produced two important and interrelated turning points in security studies: the broadening of the security field to include non-military issues and non-State actors and the growing perception of security threat labelling as a political move. Since the early 90s in particular, political and security analysts in the EU have been quick at depicting TOC not only as an economic problem but also as a security issue. With regard to the economic dimension, the European discourse mostly refers to the drastic increase in trade and the globalization of the world economy.