2013 enlargement of the European Union

The most recent enlargement of the European Union saw Croatia become the European Union's 28th member state on 1 July 2013. The country applied for EU membership in 2003, and the European Commission recommended making it an official candidate in early 2004. Candidate country status was granted to Croatia by the European Council in mid-2004. The entry negotiations, while originally set for March 2005, began in October that year together with the screening process.

The accession process of Croatia was complicated by the insistence of Slovenia, an EU member state, that the two countries' border issues be dealt with prior to Croatia's accession to the EU. Croatian public opinion was generally supportive of the EU accession process, despite occasional spikes in euroscepticism.

Croatia finished accession negotiations on 30 June 2011,^[1] and on 9 December 2011, signed the Treaty of Accession. A referendum on EU accession was held in Croatia on 22 January 2012, with 66% of participants voting in favour of joining the Union.^[2][3][4][5] The ratification process was concluded on 21 June 2013, and entry into force and accession of Croatia to the EU took place on 1 July 2013.^[6]

The EU was thus at its largest territorial extent from 2013 until 2020, when the United Kingdom left the union.