2004 年 5 月 1 日，十个新成员国加入欧盟，这是欧盟历史上人口和国家数量最多的一次扩大。这些新成员国是塞浦路斯、捷克共和国、爱沙尼亚、匈牙利、拉脱维亚、立陶宛、马耳他、波兰、斯洛伐克和斯洛文尼亚。

europarl.europa.eu/gnews.cz-RoZ_07

Multimedia Centre
20th anniversary of the 2004 enlargement of the European Union - Multimedia Centre
<p>On May 1, 2004, ten&nbsp;new member states joined the European Union, marking the&nbsp;largest enlargement in terms of people and number of countries in the EU's history. Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia joined the Union, growing from 15 to 25 members.</p> <p>The European Parliament celebrates the 20th anniversary of these ten nations joining the European Union&nbsp;and engaging in the EP's democratic process to defend the interests of European citizens.</p>