In 1918, Slovenia joined with other southern Slav states in forming the Kingdom of Serbs, Croats, and Slovenes as part of the peace plan at the end of World War I. Renamed in 1929 under a Serbian monarch, the Kingdom of Yugoslavia fell to the Axis powers during World War II. Following communist partisan resistance to German, Hungarian, and Italian occupation and elimination of rival resistance groups, socialist Yugoslavia was born under the helm of Josip Broz Tito. During the communist era, Slovenia became Yugoslavia's most prosperous republic, at the forefront of Yugoslavia's unique version of communism. Within a few years of Tito's death in 1980, Belgrade initiated plans to further concentrate political and economic power in its hands. Defying the politicians in Belgrade, Slovenia underwent a flowering of democracy and an opening of its society in cultural, civic, and economic realms to a degree almost unprecedented in the communist world. In September 1989, the General Assembly of the Yugoslav Republic of Slovenia adopted an amendment to its constitution asserting Slovenia's right to secede from Yugoslavia. On December 23, 1990, 88% of Slovenia's population voted for independence in a referendum, and on June 25, 1990, the Republic of Slovenia declared its independence. A nearly bloodless 10-day war with Yugoslavia followed. Yugoslav forces withdrew after Slovenia demonstrated stiff resistance to Belgrade.

As a young independent republic, Slovenia pursued economic stabilization and further political openness, while emphasizing its Western outlook and central European heritage. Reflecting its success in these goals, Slovenia became a member both of the North Atlantic Treaty Organization (NATO) and the European Union (EU) in March and May, respectively, of 2004. As the Organization for Security and Cooperation in Europe (OSCE) Chairman-in-Office, a continuing participant in the SFOR/EUFOR deployment in Bosnia and the KFOR deployment in Kosovo, one of the top foreign investors in the former Yugoslavia, and a charter World Trade Organization (WTO) member, Slovenia enjoys a growing regional profile and plays a role on the world stage quite out of proportion to its small size.