This articles shows that the development of the European Competition Policy was both progressive and based on a supranational dynamic. Whereas important powers were devoted to the European institutions in this field in the Treaties of Paris (1951) and Rome (1957) and in an important regulation of 1962, the Commission was not able to create a strong Competition Policy in those years. However, these decisions were important to lay the basis of the strengthening of the Commission’s powers in the Eighties. This confirms the historical institutionalism of Paul Pierson. The strengthening of the European Competition Policy stems from a supranational dynamic as it is based on the Commission’s initiatives, the Court of Justice’s ruling and on the activism of European companies. The Commission couldn’t control the whole process but it was able to take advantage of a favorable environment to strengthen its powers in the Eighties. This process has eventually peaked in the 1989 merger regulation.