European competition law is the other central player in the competition law world, so an entire chapter is devoted to understanding how it works and how to deal with it. Virtually all firms operating beyond their own national boundaries need to pay attention to it, many regimes use it as a model and reference point, and its institutions have broad and often deep influence on many others. Some aspects of the substantive law are similar to US antitrust, but the similarities are sometimes misleading. For example, EU law uses economic analysis in ways that often differ from how it is used in the US. Procedural and institutional arrangements are often complicated. They represent multiple voices, as national and EU institutions function together to create, apply, and enforce competition law. The chapter reveals how this system functions and what factors guide decisions in it. It looks, in particular, at the institutional arrangements between the EU and its member states, including the role of the European Competition Network.