All European nation states may apply for membership in the European Union. A decision to enlarge requires unanimity among all existing member states.
The original EEC of Germany, France, Italy, Belgium, Netherlands and Luxembourg has been enlarged as follows:
| Country | Applied | Joined |
| Ireland | 1961 | 1973 |
| UK | 1961 | 1973 |
| Danmark | 1961 | 1973 |
| Greece | 1975 | 1981 |
| Portugal | 1977 | 1986 |
| Spain | 1977 | 1986 |
| Austria | 1989 | 1995 |
| Sweden | 1991 | 1995 |
| Finland | 1992 | 1995 |
| Cyprus | 1990 | 2004 |
| Czech Republic | 1995 | 2004 |
| Estonia | 1995 | 2004 |
| Hungary | 1994 | 2004 |
| Latvia | 1995 | 2004 |
| Lithuania | 1995 | 2004 |
| Malta | 1990 | 2004 |
| Poland | 1994 | 2004 |
| Slovakia | 1995 | 2004 |
| Slovenia | 1996 | 2004 |
Links