1951 - Treaty of Paris:
Belgium, France, Italy, Luxembourg, Netherlands and West Germany formed the European Coal and Steel Community, a forerunner to the EEC.
1957 - Treaty of Rome:
Signed by the six founder member countries above, established the European Economic Community, forerunner of the EU. The Treaty of Rome is the bible of the European Community, providing the ultimate authority for most of its decisions.
1973 - Britain joins EEC:
With Charles de Gaulle, who vetoed the first British application in 1963, out of the picture, Edward Heath successfully negotiated British membership.
1986 - Single European Act signed, comes into force 1987:
Hugely controversial, introduced far-reaching reform. Its main objective was to facilitate completion of the single market. It included new articles on cohesion and environment policy. Significantly, it was also the first big extension of majority voting into areas where national governments had held a right of veto. Margaret Thatcher, who signed up to the treaty because it sped up decision-making on single market issues, later said she regretted doing so, because she had not been made aware of the implications for member states' right of veto. Labour always says she agreed to the biggest loss of national vetoes.
1991 - Maastricht Treaty:
EEC became the EC and the title of European Union officially came into existence. The treaty set out the timetable for the creation of the European single currency. It laid down the principle of subsidiarity and created the concept of citizenship of the EU. Britain opted out of the single currency and the social chapter guaranteeing workers' rights. On British insistence, all references to federalism were removed. It created more co-operation between member states on foreign policy, justice and home affairs. It was nearly not ratified after the Danish people rejected it in a referendum. Denmark secured an opt-out on economic and monetary union and a majority of Danes voted "yes" in 1993. The ratification process in Britain was very slow.
2000 - Treaty of Nice:
Streamlined how the EU reached decisions to pave the way for enlargement of the Union from 15 to 25 members or more. Produced an acidic row between France and Germany. At issue was the detail of how the EU would work with 10 more members - in other words, how many votes each country would have in the Council of Ministers and the European Parliament when the EU was expanded.