Maastricht Treaty or Treaty on European Union, treaty that created the European Union (EU). The treaty was approved at Maastricht in The Netherlands by the heads of government of the 12 members of the European Community (EC) in December 1991 and was signed on February 7, 1992. The 12 nations were Belgium, Denmark, France, Germany, the United Kingdom, Greece, Ireland, Italy, Luxembourg, The Netherlands, Portugal, and Spain. The treaty reflected the intention of the EC nations to broaden the scale of monetary and economic union and begin serious consideration of joint policies in regard to defense, citizenship, and the protection of the environment. Under the Maastricht Treaty, European citizenship was granted to citizens of each member state. Customs and immigration agreements were enhanced to allow European citizens greater freedom to live, work, or study in any of the member states, and border controls were relaxed. The treaty created joint foreign and monetary policies. It called for the eventual creation of a single currency, the European Currency Unit (ECU), and a central bank, which would coordinate the monetary policies of the central banks of the respective nations.

The treaty mandated that the voters of each member state had to approve the European Union, and approval was hotly debated in some states. While the people of the EC generally agreed on greater European unity regarding citizenship issues and foreign relations, there was considerable disagreement regarding the provisions requiring greater economic cooperation between members. Some countries were extremely reluctant to relinquish national control over their monetary policies, notably Denmark and the United Kingdom. On June 2, 1992, Danish voters narrowly rejected the Maastricht Treaty. However, the Danes voted their approval in May 1993. British voters ratified the treaty, but they did not generally support a common European currency. The European Union was established on November 1, 1993, after the treaty had been ratified by the 12 member states, which then became members of the EU. The EC's Parliament, Council, Commission, and Court of Justice were retained by the EU.