The EC, which is the core of the EU, originally referred to the group of Western European nations that belonged to each of three treaty organizations—the European Coal and Steel Community (ECSC), the European Economic Community (EEC), and the European Atomic Energy Community (Euratom). In 1967 these organizations were consolidated under a comprehensive governing body composed of representatives from the member nations and divided into four main branches—the European Commission (formerly the Commission of the European Communities), the Council of the European Union (formerly the Council of Ministers of the European Communities), the European Parliament, and the European Court of Justice.

Although the EU has no single seat of government, many of its most important offices are in Brussels, Belgium. The European Commission, which has executive and some legislative functions, is headquartered there, as is the Council of the European Union; it is also where the various committees of the European Parliament generally meet to prepare for the monthly sessions in Strasbourg, France. In addition to the four main branches of the EU's governing body, there are the Court of Auditors, which oversees EU expenditures; the Economic and Social Committee, a consultative body representing the interests of labor, employers, farmers, consumers, and other groups; and the European Council, a consultative but highly influential body composed primarily of the president of the Commission and the heads of government of the EU nations and their foreign ministers.

The history of the EU began shortly after World War II, when there developed in Europe a strong revulsion against national rivalries and parochial loyalties. While postwar recovery was stimulated by the Marshall Plan, the idea of a united Europe was held up as the basis for European strength and security and the best way of preventing another European war. In 1950 Robert Schuman, France's foreign minister, proposed that the coal and steel industries of France and West Germany be coordinated under a single supranational authority. France and West Germany were soon joined by four other countries—Belgium, Luxembourg, the Netherlands, and Italy—in forming (1952) the ECSC. The EEC (until the late 1980s it was known informally as the Common Market) and Euratom were established by the Treaty of Rome in 1958. The EEC, working on a large scale to promote the convergence of national economies into a single European economy, soon emerged as the most significant of the three treaty organizations.

The Brussels Treaty (1965) provided for the merger of the organizations into what came to be known as the EC and later the EU. Under Charles de Gaulle, France vetoed (1963) Britain's initial application for membership in the Common Market, five years after vetoing a British proposal that the Common Market be expanded into a transatlantic free-trade area. In the interim, Britain had engineered the formation (1959) of the European Free Trade Association. In 1973 the EC expanded, as Great Britain, Ireland, and Denmark joined. Greece joined in 1981, and Spain and Portugal in 1986. With German reunification in 1990, the former East Germany also was absorbed into the Community.

The Single European Act (1987) amended the EC's treaties so as to strengthen the organization's ability to create a single internal market. The Treaty of European Union, signed in Maastricht, the Netherlands, in 1992 and ratified in 1993, provided for a central banking system, a common currency to replace the national currencies (the euro, see European Monetary System), a legal definition of the EU, and a framework for expanding the EU's political role, particularly in the area of foreign and security policy. The member countries completed their move toward a single market in 1993 and agreed to participate in a larger common market, the European Economic Area (est. 1994), with most of the European Free Trade Association (EFTA) nations. In 1995, Austria, Finland, and Sweden, all former EFTA members, joined the EU, but Norway did not, having rejected membership for the second time in 1994.

A crisis within the EU was precipitated in 1996 when sales of British beef were banned because of "mad cow disease" (see prion). Britain retaliated by vowing to paralyze EU business until the ban was lifted, but that crisis eased when a British plan for eradicating the disease was approved. The ban was lifted in 1999, but French refusal to permit the sale of British beef resulted in new strains within the EU. In 1998, as a prelude to their 1999 adoption of the euro, 11 EU nations established the European Central Bank. The euro was introduced into circulation in 2002 by 12 EU nations; additional EU nations have since adopted it.

The EU was rocked by charges of corruption and mismanagement in its executive body, the European Commission (EC), in 1999. In response the EC's executive commission including its president, Jacques Santer, resigned, and a new group of commissioners headed by Romano Prodi was soon installed. In actions taken later that year the EU agreed to absorb the functions of the Western European Union, a comparatively dormant European defense alliance, thus moving toward making the EU a military power with defensive and peacekeeping capabilities.

The installation in Feb., 2000, of a conservative Austrian government that included the right-wing Freedom party, whose leaders had made xenophobic, racist, and anti-Semitic pronouncements, led the other EU members to impose a number of sanctions on Austria that limited high-level contacts with the Austrian government. Enthusiasm for the sanctions soon waned, however, among smaller EU nations, and the issue threatened to divide the EU. A face-saving fact-finding commission recommended ending the sanctions, stating that the Austrian government had worked to protect human rights, and the sanctions were ended in September.

In 2003 the EU and ten non-EU European nations (Estonia, Latvia, Lithuania, Poland, the Czech Republic, Slovakia, Hungary, Slovenia, Cyprus, and Malta) signed treaties that resulted in the largest expansion of the EU the following year, increasing the its population by 20% and its land area by 23%. Most of the newer members are significantly poorer than the largely W European older members. The old and new member nations at first failed to agree on a constitution for the organization; the main stumbling block concerned voting, with Spain and Poland reluctant to give up a weighted system of voting scheduled for 2006 that would give them a disproportionate influence in the EU relative to their populations. In Oct., 2004, however, EU nations signed a constitution with a provision requiring a supermajority of nations to pass legislation. The constitution, which needed to be ratified by all members to come into effect, was rejected by voters in France and the Netherlands in 2005, leading EU leaders to pause in their push for its ratification.

Meanwhile, in 2003 the EU embarked, in minor ways, on its first official military missions when EU peacekeeping forces replaced the NATO force in Macedonia and were sent by the United Nations to Congo (Kinshasa); the following year the EU assumed responsibility for overseeing the peacekeepers in Bosnia. EU members also took steps toward developing a common defense strategy independent of NATO, and agreed in 2004 to admit Bulgaria and Romania in 2007. José Manuel Barroso succeeded Prodi as president of the European Commission late in 2004. Accession talks with Turkey were partially suspended in Dec., 2006, over the issue of Turkish relations with Cyprus because Turkey was unwilling to open its ports to Cypriot trade unless the EU eased its trade restrictions on North Cyprus.

The EU opted for incremental reforms over a new constitution in 2007, when member nations signed the Lisbon Treaty. Once ratified, the treaty will come into force in 2009 and reorganize the European Council, establish a single EU foreign policy official, and reform the EU's system of voting, among other changes. The reforms will be phased in through 2017.

See W. Diebold, The Schuman Plan (1959); R. L. Heilbroner, Forging a United Europe (Public Affairs Pamphlet, 1961); B. Morris and K. Boehm, ed., The European Community (1986); H. Wallace and A. Ridley, Europe: The Challenge of Diversity (1986); M. Burgess, Federalism and European Union (1989); and D. Dinan, A Historical Dictionary of the European Community (1993).