The European Federation, also referred to as the United States of Europe (USE), European State, or Federal Europe, is a hypothetical scenario of European integration leading to the formation of a sovereign superstate, organised as a federation of the member countries of the European Union (EU), as contemplated by political scientists, politicians, geographers, historians, futurologists and fiction writers. At present, while the EU is not a federation, various academic observers regard it as having some of the characteristics of a federal system.

European integration is the process of industrial, economic, political, legal, social, and cultural integration of states wholly or partially in Europe, or nearby. European integration has primarily but not exclusively come about through the European Union and its policies.