On 1 May 2004 the European Union was enlarged with ten new Member States; Czech Republic, Estonia, Cyprus, Hungary, Latvia, Lithuania, Malta, Poland, Slovenia and the Slovak Republic. Norway supported the enlargement of the EU, seeing it as one of the most important contributions to peace, stability and development in Europe.
Norway was associated with the EU enlargement through the parallel enlargement of the European Economic Area (EEA), in which Norway is a part. Norway and the two other EEA EFTA States, the European Commission and the Acceding States opened negotiations on the EEA enlargement on 9 January 2003. The negotiations were successfully concluded with the initialling of the EEA Enlargement Agreement in Brussels on 3 July 2003. The EEA Enlargement Agreement went through national ratification processes on 1 May 2004. EU and the EEA was enlarged simultaneously.
Within the enlarged EEA, trade relations between the EEA EFTA States and the new EU Member States was strengthened considerably. The enlarged EEA comprised some 475 million inhabitants, making it the world's largest internal market.
On 1 January 2007 Bulgaria and Romania became members of the European Union and on 1 August 2007 the EEA was further enlarged with the two new member countries.
The EEA Enlargement Agreement ensures the participation of the twelve new EU Member States in the EEA and provides for Financial Mechanisms through which the three EEA EFTA States jointly and Norway bilaterally is contributing substantially to reducing social and economic disparities in Europe. Within the scope of the EEA, the EEA Enlargement Agreement also ensures application of the same adaptations and transitional arrangements in the EEA as those laid down in the EU Treaty of Accession.