Since 1990, altogether 31 EU-related referendums have been organized across Europe. Denmark, Ireland and Switzerland have organized four referendums each, while most countries (Austria, the Czech Republic, Estonia, Finland, France, Hungary, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Slovakia, Slovenia, Spain and Sweden) have only held one or two referendums in the period in question. Of the 31 countries involved in this study, 12 countries have not conducted any EU-related referendums since 1990: Belgium, Bulgaria, Cyprus, Germany, Greece, Iceland, Italy, Liechtenstein, Portugal, Romania and the United Kingdom.

Referendums on the accession to the European Union (1994/2003):
In 1994, referendums regarding the accession to the European Community (EC) were carried out in Austria, Finland, Norway and Sweden. Accession was rejected in Norway only. In 2003, referendums were organized in the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia in 2003. In all these countries, EU-accession was accepted. The countries entered the Union in 2004 together with Cyprus, which did not organize a referendum.

Austria 1994  [Abstract]                             
Finland 1994 [Abstract]      
Norway 1994 [Abstract]
Sweden 1994 [Abstract]

Czech Republic 2003 [Abstract]
Estonia 2003 [Abstract]
Hungary 2003 [Abstract]
Latvia 2003 [Abstract]
Lithuania 2003 [Abstract]
Malta 2003 [Abstract]
Poland 2003 [Abstract]
Slovakia 2003 [Abstract]
Slovenia 2003 [Abstract]

Referendum on the Maastrict Treaty (1992/1993):
Denmark, France and Ireland held referendums on the Maastrict Treaty. Owing to the rejection of the Treaty in Denmark, it was re-negotiated and a new referendum was held in 1993.

Denmark 1992 [Abstract]
Denmark 1993 [Abstract]
France 1992 [Abstract]
Ireland 1992 [Abstract]

Referendums on the Amsterdam Treaty (1998):
Denmark and Ireland. In both cases the Treaty was accepted.

Denmark 1998 [Abstract]
Ireland 1998 [Abstract]

Referendum on the Nice Treaty (2001/2002):
The Nice Treaty was first rejected (2001) but later accepted (2002) in referendums in Ireland.

Ireland 2001 [Abstract]
Ireland 2002 [Abstract]

Referendum on the adoption of the Euro (2000/2003):
Denmark and Sweden held referendums on the accession to the European Monetary Union (EMU) in 2000 and 2003, respectively. In both countries, the Euro was rejected.

Denmark 2000 [Abstract]
Sweden 2003 [Abstract]

Referendum on the EU Constitution (2005):
France, the Netherlands, Luxembourg and Spain held referendums on the Constitution of Europe. The Constitution was rejected in France and the Netherlands. In six countries (Czech Republic, Denmark, Ireland, Poland, Portugal and United Kingdom) referendums have been either cancelled or postponed indefinitely. As for the remaining EU member states, the Constitution has been subject to parliamentary approval in which it has been accepted in all but two countries (the Czech Republic (which cancelled the referendum) and Sweden where the case has been postponed).

France 2005 [Abstract]
The Netherlands 2005 [Abstract]
Luxembourg 2005 [Abstract]
Spain 2005 [Abstract]

Referendums in Switzerland: Switzerland has organized four EU related referendums:
In 1992 (on Switzerlands accession to the European Economic Area, rejected), 2000 (bilaterat agreement), and two referendums in 2005 (on the accession into the Schengen area and the Dublin Convention).

Switzerland 1992 [Abstract]
Switzerland 2000 [Abstract]
Switzerland 2005 [Abstract]
Switzerland 2005 [Abstract]

Survey data related to EU referendums:

Eurobarometer

Eurobarometer Flash reports:

Eurobarometer, Flash 168 (Spain) (2005). The European Constitution: post-referendum survey in Spain, European Commission.