With the internationalization of anticompetitive business activity, national competition laws and policies proved to be insufficient to protect competition in free markets. To cope with the problems created by international anticompetitive conduct, states and/or national regulators started to take part in various arrangements concerning the issue. Today, there are different forms of internationalization of competition law and policy such as extraterritorial application of domestic laws and policies and certain cooperation and convergence mechanisms. Moreover, various actors take part in the process: states, regulators, international organizations, firms etc. This thesis aims to analyze the important factors of internationalization of competition law and policy so that the reasons behind the current state of the internationalization process can be understood. Furthermore, four main International Political Economy theoretical perspectives are utilized to provide a new insight for and a further understanding of internationalization of competition law and policy.