The following countries have joined the first six: Denmark, Ireland and the United Kingdom in 1973, Greece in 1981, Spain and Portugal in 1986, Austria, Finland and Sweden in 1995, and the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia in 2004. and has seen its scope expand to cover new areas through the establishment of the Economic Community and the Atomic Energy (Euratom) Community (Treaties of Rome of 25 March 1957
Pirmajām sešām valstīm pievienojās: Dānija, Īrija un Apvienotā Karaliste – 1973. g., Grieķija – 1981. g., Spānija un Portugāle – 1986. g., Austrija, Somija un Zviedrija – 1995. g., Čehija, Igaunija, Kipra, Latvija, Lietuva, Ungārija, Malta, Polija, Slovēnija un Slovākija – 2004.g. un paplašināt savu darbību, aptverot