The EU has long viewed the enlargement process as an historic opportunity to further the integration of the continent by peaceful means. Analysts contend that the carefully managed process of enlargement is one of the EU's most powerful policy tools and has helped transform former dictatorships such as Spain and many of the former communist states of Central and Eastern Europe into stable democracies and free market economies. The EU maintains that the enlargement door remains open to any European country, including Turkey and those of the Western Balkans, able to fulfill the EU's political and economic criteria for membership. Croatia is the newest member state, joining the EU on July 1, 2013. Evolution of the European Union

The EU is the latest stage in a process of European integration aimed at promoting political reconciliation and economic prosperity throughout the European continent. At the same time, EU enlargement is very much a political process; most all steps on the path to accession require the unanimous agreement of the existing member states. As such, a prospective EU candidate's relationship or conflicts with individual member states may significantly influence a country's EU accession prospects and timeline. Current EU Candidates

Currently, five countries are considered by the EU as official candidates for membership: Iceland, Macedonia, Montenegro, Serbia, and Turkey. Iceland's accession negotiations, however, have been on hold since May 2013, following the election of a new center-right coalition government largely opposed to EU membership. Macedonia has not yet secured a start date for accession negotiations. For years, this has been due largely to a long-running disagreement with Greece over the country's official name. The remaining Western Balkan states of Albania, Bosnia-Herzegovina, and Kosovo are all officially recognized by the EU as potential candidates, but their accession prospects and timetables vary (see the text box on the next page for more information); most analysts believe that it will likely be many more years before any of these countries are ready to join the EU. Despite Croatia's recent accession and the EU's membership commitment to the other Western Balkan countries, experts assert that a number of European leaders and many EU citizens remain cautious about further EU enlargement. Apprehensions about continued EU enlargement seem to be driven by several issues. Nevertheless, such concerns persist, especially when considering the accession of big, relatively less affluent countries such as Turkey or possibly Ukraine in the longer term. Some key EU member states may fear that an ever-expanding Union could ultimately weaken their ability to set the tone and agenda in EU institutions and to drive EU policies. Moreover, commentators suggest that the EU's recent economic problems and sovereign debt crisis—which have hit the countries of the Eurozone particularly hard—could potentially slow future rounds of EU enlargement. Administrations and many Members of Congress have long backed EU enlargement, believing that it serves U.S. interests by advancing democracy and economic prosperity, and thereby creating strong European political allies and trading partners. Over the years, the only significant U.S. criticism of the EU's enlargement process has been that the Union was moving too slowly, especially with respect to Turkey. Successive U.S. Periodically, however, U.S. pressure to promote Turkey's EU accession prospects has generated tensions with the EU. Some U.S. officials remain concerned that "enlargement fatigue," as well as the EU's financial crisis, could hinder additional EU expansion.
The European Union (EU) has long viewed the enlargement process as an extraordinary opportunity to promote political stability and economic prosperity in Europe. Since 2004, EU membership has grown from 15 to 28 countries, bringing in most states of Central and Eastern Europe and fulfilling an historic pledge to further the integration of the continent by peaceful means. Croatia is the EU's newest member, acceding to the EU on July 1, 2013.
Analysts contend that the carefully managed process of enlargement is one of the EU's most powerful policy tools, and that, over the years, it has helped transform many European states into functioning democracies and more affluent countries. The EU maintains that the enlargement door remains open to any European country that fulfills the EU's political and economic criteria for membership. At the same time, EU enlargement is also very much a political process; most all significant steps on the long path to accession require the unanimous agreement of the existing 28 member states. As such, a prospective EU candidate's relationship or conflicts with individual member states may also influence a country's EU accession prospects and timeline.
Currently, five countries are recognized by the EU as official candidates for membership: Iceland, Macedonia, Montenegro, Serbia, and Turkey. All are at different stages of the accession process. While Montenegro and Serbia have only recently begun accession negotiations, Turkey's accession talks have been underway since 2005. Macedonia's accession negotiations have not yet started largely because of an ongoing dispute with Greece over the country's official name. And EU accession talks with Iceland, although relatively advanced, have been on hold since May 2013, when a new Icelandic government largely opposed to EU membership took office. The EU also considers the remaining Western Balkan states of Albania, Bosnia-Herzegovina, and Kosovo as potential EU candidates, but most experts assess that it will likely be many years before any of these countries are ready to join the EU.
Despite the EU's professed commitment to enlargement, some EU policy makers and many EU citizens are cautious about additional expansion, especially to Turkey or countries farther east, such as Georgia or Ukraine, in the longer term. Worries about continued EU enlargement range from fears of unwanted migrant labor to the implications of an ever-expanding Union on the EU's institutions, finances, and overall identity. Such qualms are particularly apparent towards Turkey, given its large size, predominantly Muslim culture, and comparatively less prosperous economy.
Successive U.S. Administrations and many Members of Congress have long backed EU enlargement, believing that it serves U.S. interests by advancing democracy and economic prosperity throughout the European continent. Over the years, the only significant U.S. criticism of the EU's enlargement process has been that the Union was moving too slowly, especially with respect to Turkey. Some U.S. officials are concerned that "enlargement fatigue" as well as the EU's economic and financial troubles, which have hit the countries that use the EU's common currency (the euro) particularly hard, could potentially slow future rounds of EU enlargement.
The status of EU enlargement and its implications for both the EU itself and U.S.-EU relations may be of interest to the 113th Congress. For additional information, see also CRS Report RS21372, The European Union: Questions and Answers, by [author name scrubbed]; and CRS Report RS22517, European Union Enlargement: A Status Report on Turkey's Accession Negotiations, by [author name scrubbed].