Updated: 13/03/2024

Enlargement of the European Union

The European Union[1] (EU), which the six countries laid the foundations for today by establishing the European Coal and Steel Community and the European Economic Community, has gone through a number of successive widening and deepening processes, and transformed into a 27-member transnational structure that implements common policies in many areas. In this process, the EU has become a much stronger Union in terms of political, economic and geopolitical terms by incorporating new member states, each of which has a different nature, and thus increased its effectiveness in the international system.

Historically, the enlargement policy is often referred to as the most important and most successful foreign policy instrument in the EU literature, both in terms of spreading the transformative power of the EU to its environment and also having a major role in the internal transformation of the EU.

The enlargement policy of the EU, in parallel with the deepening process of the Union, has taken its present form by being reshaped with each new enlargement wave. In particular, the last enlargement of Central and Eastern European countries became a leading step for the enlargement policy to reach its current position and institutionalization of the ‘conditionality’ principle. Accession conditionality can be briefly defined as the sum of the obligations that the countries applying to become a member of the EU have to undertake before their accession.

The criteria defined at the Copenhagen European Summit in 1993, known as the ‘Copenhagen Criteria’, serve as a basic guide for the countries wishing to become a member of the Union. The EU takes the decision to start negotiations with candidate countries only if they fulfill the requirements, which are also known as the Copenhagen “Political” Criteria; including democracy, the rule of law, human rights and the existence of institutions that guarantee minority rights.

On the other hand, at the Madrid Summit held on 15-16 December 1995, it was stated that the candidate states for the Union are not only responsible for transposing the EU acquis into their internal law, but are also responsible for establishing the administrative and legal structures in charge of implementing the legislation they have harmonized and this was presented as a new condition for accession. This condition, called the administrative capacity criteria, is also called the Madrid Criteria.

In addition to the Copenhagen Criteria and the Madrid Criteria, in Agenda 2000, establishing good neighborly relations was presented as a condition of accession. Accordingly, all candidate countries should resolve border disputes between themselves and with third countries before joining the Union and, if necessary, apply to the International Court of Justice.

Additionally, with the start of negotiations between Croatia and our country, the European Commission has started to introduce ‘technical criteria’ for the opening and closing of the negotiation headings known as ‘chapters’, each of which represents the different policy areas of the EU. The procedures for transferring the opening and closing benchmarks to the candidate countries and assessing whether they have been fulfilled were also an important step for the accession process to take its present form.

In the negotiation process of the Western Balkan countries, which are currently running, the European Commission has developed a new approach to the Chapter 23- Judiciary and Fundamental Rights and the Chapter 24- Justice, Freedom and Security. In the framework of the ‘New Approach’, it was agreed that the Chapters 23 and 24 should be addressed as early as possible and remain open throughout the negotiation process in order to provide the candidate country with the necessary time to establish the necessary reform program; if the progress in these chapters falls behind the progress in the general negotiation process, the opening and closing of the other chapters may be affected.

The EU has not only provided the candidate countries with the conditions it expects them to fulfill before membership, but has been systematically guided and evaluated the work that candidate countries have been required to meet the membership conditions since the fifth enlargement, which will be explained below, through various meetings, documents and monitoring mechanisms.

Lastly, on 5 February 2020 European Commission presented a Communication on “Enhancing the accession process - A credible EU perspective for the Western Balkans” and has made important methodological changes in enlargement policy. These methodological changes are mainly for the accession process of North Macedonia and Albania, but if they want Serbia and Montenegro could also be part of this new method. Commission’s proposals are adopted by member states on 25 March 2020 EU General Affairs Council. Besides on 15 May 2020, Montenegro announced that they accepted to be part of the new method.

Click here for information and documents related to Türkiye's accession process.

History of Enlargement

The enlargement process, basically can be divided into 6 periods.

First Enlargement (Britain, Ireland, Denmark – 1973)

Britain, Ireland and Denmark applied to the EU in 1961 for membership. While other countries, other than France, approached the accession of Britain positively, French President Charles De Gaulle opposed this membership on the grounds that Britain was quite different from the Continental Europe, suffered from economic difficulties, was dependent on the United States in military and diplomatic terms, and hence would prevent the development of the Union. Britain reapplied in 1967 and was not accepted again for the same reasons. The enlargement process for these countries began after De Gaulle's resignation from the French Presidency in 1969 and ended on 1 January 1973, with the accession to the EU.

The Second Enlargement (Greece – 1981)

Relations with Greece, which signed the Association Agreement with the EU in 1961, were suspended when the Military Junta seized power in 1967. Greece became a democratic government after the military junta left the administration to civilians in 1974 and applied to the EU for full membership in 1975. In the EU, the application was met with concerns that Greece was not ready to become a member both politically and economically and did not share common values with other member states. After a six-year negotiation process, member states began to argue that instead of excluding Greece, its democratization and economic development could be achieved more effectively within the Union, and Greece became a member of the EU on 1 January 1981.

Third Enlargement (Spain, Portugal – 1986)

The third enlargement, also known as the Iberian Enlargement, took place when Spain and Portugal joined the EU on 1 January 1986. When these two countries applied for membership, there were a lot of discussions on whether they would be accepted for membership because of the differences in political and economic development between them and the Union. The concern that Spain and Portugal could create economic burden on the member states both in terms of agriculture and the free movement of workers, has occupied the agenda of the EU for a long time; however, the geopolitical importance of the Mediterranean for the EU and the success of the enlargement policy carried out at that time have helped to overcome all these discussions.

Fourth Enlargement (Austria, Finland, Sweden – 1995) 

The fourth enlargement of the EU is closely related with the Cold War and the developments took place afterwards. Austria, Finland and Sweden, who pursued neutrality during the war, decided to join the EU when the Cold War was over. This enlargement process went smoothly, as these countries were culturally part of Europe and had established close economic ties with the European Community before the candidacy. Austria, Finland and Sweden became EU members on 1 January 1995.

The Fifth Enlargement (Hungary, Poland, Czech Republic, Slovakia, Slovenia, Latvia, Lithuania, Estonia, Malta, Greek Cypriot Administration of Southern Cyprus – 2004) (Romania, Bulgaria – 2007)

The end of the Cold War was a real turning point for the European continent. The end of the half-century division was celebrated with enthusiasm all over Europe, and the Central and Eastern European Countries, that are outside European integration without being bound to their will, and Malta and the Greek Cypriot Administration of Southern Cyprus, began to apply for EU membership. However, the fifth enlargement process, which is very different from the previous enlargements in terms of both the quality and quantity of the candidate countries and the depth reached by the European integration, has been quite painful both for the candidate countries and for the EU.

Countries that have applied for membership in this enlargement process rearrange almost every area of social life within the framework of the Copenhagen criteria for membership as mentioned above. The EU has carried out the enlargement process much more comprehensively than other enlargements with its own guiding and monitoring mechanisms.

The EU Council then initiated the process of enlargement at the Luxembourg Summit in December 1997. For the first time in this process, the following twelve countries received candidate status: Bulgaria, Greek Cypriot Administration of Southern Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Romania, Slovak Republic and Slovenia.

On 31 March 1998, on the recommendation of the European Commission, negotiations began with six countries, namely the Greek Cypriot Administration of Southern Cyprus, the Czech Republic, Estonia, Hungary, Poland and Slovenia.

Malta reinstated the application for membership, which it frozen in 1996, in October 1998. In December 1999, the EU Council confirmed the comprehensiveness of the accession process at the Helsinki Summit and, on the recommendation of the European Commission, decided to start more formal accession negotiations with six candidate countries: Bulgaria, Latvia, Lithuania, Malta, Romania and the Slovak Republic. Accession negotiations with these six countries were officially launched on 15 February 2000. The EU Council in Helsinki confirmed Türkiye as a candidate to join the Union on the same criteria as the other candidate countries that have confirmed.

On 1 May 2004, the most comprehensive enlargement of EU history was completed with the official accession of 10 new member states (Czech Republic, Hungary, Poland, Slovakia, Slovenia, Lithuania, Latvia, Estonia, Malta and Greek Cypriot Administration of Southern Cyprus) to the EU.

Bulgaria and Romania became members on 1 January 2007.

The Sixth Enlargement (Croatia – 2013)

Applying for candidacy in 2003, Croatia, as well as our country, started accession negotiations on 3 October 2005. Croatia has signed the Accession Treaty on 9 December 2011, after Slovenia has unblocked its various chapters. Along with Croatia becoming a member in 2013, the EU has become a 28-member Union. However, after the United Kingdom’s exit from the EU on 31 January 2020, today the Union has 27 member states.

Candidate and Potential Candidate Countries

In the current situation there are six countries that are candidates for EU membership other than Türkiye: North Macedonia, Montenegro, Serbia and Albania, Ukraine and Moldova. The EU continues its accession negotiations with Türkiye, Montenegro, Serbia, North Macedonia and Albania . 

Bosnia and Herzegovina, Kosovo and Georgia are potential candidate countries.

Iceland, which started accession negotiations with the EU on 17 June 2010 and opened 27 of the 35 negotiation chapters and temporarily closed 11 chapters, withdrew its application for EU candidacy on 12 March 2015. The Iceland case is the first in the history of enlargement in terms of withdrawing the application for membership after coming a long way in the negotiation process.

Current Situation in the Enlargement Policy of the European Union



Application Date    for EU Membership

    Date of Candidacy

Starting Date of Negotiations


14 April 1987

10-11 December 1999

3 October 2005

North Macedonia

22 March 2004

15-16 December 2005

Council Decision: 25 March 2020


15 December 2008

17 December 2010

29 June 2012


22 December 2009

1 March 2012

17 December 2013


24 April 2009

27 June 2014

Council Decision: 25 March 2020


28 February 2022

24 June 2022



3 March 2022

24 June 2022



Potential Candidate Country

 Status for Potential Candidacy

Signing of Stabilization and Association Agreement

Entry into force of the Stabilization and Association Agreement

Bosnia and Herzegovina

20 June 2003

16 June 2008

1 June 2015


18 February 2008

27 October 2015

1 April 2016


24 June 2022

27 June 2014

1 July 2016

For detailed information about the candidate countries, please click here.

Please click here for detailed information about potential candidate countries.

Please click here for the enlargement page of the European Commission.




[1] Regardless of how it is called in the historical process, in the text, it will be referred to as the European Union.

Updated: 13/03/2024 / Hit: 642,428