Transnational criminal operations--such as drug smuggling, human trafficking, terrorism, and Internet-related crimes--have increased the need for criminal justice personnel and institutions to establish structures, policies, and procedures of cooperation. This is necessary in order for jurisdictions in which crimes occur to pursue and interview suspects and witnesses in other jurisdictions, as well as to have access to documentary evidence that exists in jurisdictions other than where victimizations occur. This chapter describes some of the existing institutions and structures of international cooperation in addressing transnational crime. These include the United Nations, Interpol, Europol, and the EU. The chapter also describes the work of the European Ombudsman, Eurojust, the European Judicial Network, and the European Judicial Network on Civil and Commercial Cases. Some tools of international cooperation discussed are the European arrest warrant, extradition, mutual judicial assistance, the EU Anti-fraud Office, and the Financial Action Task Force. Some sections of the chapter focus on the United Kingdom's structures for international cooperation in addressing organized crime and terrorism. The author notes that national jurisdictions and transnational bodies have been slow in changing their structures and allocating resources to the most effective means of addressing transnational crime and terrorism. All international bodies, from the United Nations to the EU, have fallen short of the challenges posed by transnational crime. This has set the stage for the possibility of the creation of an international coordinating body composed of countries whose citizens are most at risk for victimization by international criminals and terrorists. 10 notes and 19 references