Treaty of Paris
Signed 1951 - Expired 2002

Established the European Coal and Steel Community (ECSC), which subsequently became part of the European Union.
 

Treaty of Rome
Signed 1957
 

Established the European Economic Community (EEC)

Treaty of Brussels
Signed 1965
Replaced by Amsterdam Treaty in 1997
 

This treaty is regarded by some as the real beginning of the modern European Union. The term European Communities or EC also came into use from this time onward.

Maastricht Treaty
Signed 1992

Led to the creation of the European Union and introduced the Euro.

Treaty of Amsterdam
Signed 1997

Increased powers for the European Parliament and the beginnings of a common foreign and security policy (CFSP) and the reform of the institutions in the run-up to enlargement.

Treaty of Nice
Effective Feb 2003
 

Amended previous treaties to withstand the Enlargement of the European Union.
 

Treaty of Lisbon
Effective Jan 2009

Replaces the defunct EU constitution rejected by French and Dutch voters in 2005, will take effect in January 2009, enabling the EU to face up to the challenges of the globalization era more confidently.