The EU comprises 27 countries. They are set out below, under the dates they joined.

• 1958
  
  Belgium, France, (West) Germany, Italy, Luxembourg, Netherlands
• 1973
  
  Denmark, Ireland, UK
• 1981
  
  Greece
• 1986
  
  Portugal, Spain
• 1995
  
  Austria, Finland, Sweden
• 2004
  
  Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, Slovenia
• 2007
  
  Romania, Bulgaria