Union membership is open to any European country with stable democratic government, a good
human rights record, a properly functioning market economy, and the macroeconomic fitness to fulfil the obligations of membership. Candidates must
have the capacity to fulfil and implement EU laws and regulations (known as the "acquis communautaire").
To date, four enlargements have taken place in the evolution of the European Union:
- Denmark, Ireland and the United Kingdom joined the original six European Community members in 1973
- Greece joined in 1981
- followed by Spain and Portugal in 1986
- Austria, Finland, and Sweden acceded to the European Union on January 1, 1995. Norway had also negotiated and signed an accession treaty in 1994 but Norwegian voters narrowly rejected membership in a referendum.
- Although it was not officially an enlargement, the five Laender of the former German Democratic Republic entered the Union as part of a united Germany on October 3, 1990.
- The European Union is currently preparing for a fifth enlargement towards Central and Eastern Europe.