International criminality has been a challenging phenomenon for national police forces for years. States have developed international police cooperation relations and extradition instruments in order to fight international criminal activity. This treatise explores the reasons for the rise in transnational organized crime activities in Europe and presents an in-depth explanation concerning the emergence, mandates, and structures of multilateral police collaboration systems such as Interpol, Trevi, Schengen, and Europol. Since the extradition has become an inseparable part of international policing, this study examines the improvements in extradition procedure and emphasizes the importance of extradition. Finally this study compares traditional (European Convention on Extradition of 1957) and new (European Arrest Warrant) extradition systems.