2004 in the European Union

Events from the year 2004 in the European Union.

Incumbents

 * 🇪🇺 Commission President
 * 🇮🇹 Romano Prodi (to 22 November)
 * José Manuel Barroso (since 22 November)
 * 🇪🇺 Council Presidency
 * 🇮🇪 Ireland (January–June)
 * The Netherlands (July–December)
 * 🇪🇺 Parliament President
 * 🇮🇪 Pat Cox (to 30 July)
 * 🇪🇸 Josep Borrell (since 30 July)
 * 🇪🇺 High Representative
 * 🇪🇸 Javier Solana

Events

 * 1 May: 2004 Enlargement (Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia).
 * 10–13 June: 2004 European Parliament election expanding the Commission.
 * 22 July: The European Parliament approves José Manuel Barroso as President.
 * 29 October: Delegates of the 25 member states sign the European Constitution in Rome.
 * 1 November: Original date for Barroso to enter office delayed due to parliamentary opposition to some of his Commissioners. A new college is later submitted.
 * 18 November: The European Parliament approves the Barroso Commission.
 * 22 November: Barroso Commission took office.