Enlargement is the process whereby countries join the EU. Since it was founded in 1957, the EU has grown from 6 member countries to 28.
Any European country that respects the principles of liberty, democracy, respect for human rights, fundamental freedoms and the rule of law may apply to become a member of the EU. A valid application triggers a series of evaluations in the light of the so-called Copenhagen criteria . These may result in a country being given the status of a 'candidate country'. If the country is sufficiently advanced in fulfilling the Copenhagen criteria, accession negotiations start: the applicants have to implement the body of EU law before they may become a member state.
When this process is completed, an 'accession treaty' is drawn up and signed by the candidate country and the EU Member States. The country can join the EU only once this treaty has been formally approved by the European Parliament and ratified by the candidate country and all the existing Member States.
There are currently seven candidate countries and potential candidates to which the EU has offered the prospect of membership.
The last country which has successfully completed the accession negotiations is Croatia. It became a member of the EU on 1 July 2013.
The former Yugoslav Republic of Macedonia became a candidate country in 2005.
Montenegro has been a candidate country since 2010.
Serbia has been a candidate country since 2012. It submitted its application for membership in 2009.
Turkey has been a candidate country since 1999.
Albania has been a candidate country since 2014. It submitted its application for membership in 2009.
Bosnia and Herzegovina has been a potential candidate country since 2003.
Kosovo has been a potential candidate since 2008.
* This designation is without prejudice to positions on status, and is in line with UNSCR 1244 and the ICJ Opinion on the Kosovo declaration of independence.
Each year in the autumn, the European Commission adopts its 'Enlargement package': an overview of enlargement strategy and progress achieved towards EU accession in the Western Balkans (Albania, Bosnia and Herzegovina, the former Yugoslav Republic of Macedonia, Montenegro, Serbia as well as Kosovo) and Turkey.
Progress report 2015
On 10 November 2015 the European Commission published its annual overview of enlargement policy and the progress made towards EU accession in the Western Balkans and Turkey.