For many years the various parties of the non-socialist Left worked together in the same group in the European Parliament. In 1989 four parties, the Italian CP, the United Left of Spain, the SPP of Denmark and Synaspismos of Greece decided to form a group called the European United Left (GUE, Gauche Unitaire Européenne).
When the Italian CP, renamed PDS, decided to join the Socialist International in 1991, the latter joined the Socialist Group in the European Parliament. A process of gathering together all the forces of the non-socialist Left then began. This alliance, enlarged to include other parties, was established as a political group at the beginning of the fourth parliamentary term in 1994 under the name Confederal Group of the European United Left (GUE). The member parties were: United Left of Spain, the Communist Party of France, Communist Refoundation of Italy; the Communist Party of Portugal, the Communist Party of Greece, and Synaspismos of Greece.
Following enlargement of the EU to the Nordic countries and Austria in January 1995, the group expanded to include: the Left Party (VP) of Sweden, and the Left Alliance (Vas) of Finland. At the same time the Socialist Peoples' Party (SF) of Denmark joined the group and together with the Swedish and Finnish parties formed the Nordic Green Left (NGL) component within the group.
The group was renamed the Confederal Group of the European United Left/Nordic Green Left, with GUE/NGL as the standard acronym. In 1998 Ken Coates, a distinguished MEP who was expelled from the British Labour Party, joined the GUE/NGL from the PES Group, and Carlo Ripa Di Meana, an Italian MEP and former Environment Commissioner, joined the group from the Greens to bring the GUE/NGL to 34 MEPs from eight countries.
In the European elections of 1999, all the outgoing parties were successful in securing representation in the new Parliament. They were joined in the group by the Socialist Peoples' Party (SF) of Denmark and the Party of Democratic Socialism (PDS) of Germany, which had previously been associate member parties. The group also welcomed a third party from Greece, the DIKKI, as full member and five MEPs from France, elected on the LO-LCR list, as associate members.
Parties not currently represented in the European Parliament but having close cooperative arrangements with the GUE/NGL include the Socialist Left Party (SV) of Norway and Dei Lenk in Luxembourg.
During 2001 two MEPs, Ilka Schröder (DE) from the Green Group and Freddy Blak (DK) from the Group of the Party of European Socialists, joined the GUE/NGL.
During 2002, six MEPs, Ole Krarup and Jens Okking (DK) from the EDD Group and Gérard Caudron, Michel Dary, Sami Nair, et Michel-Angel Scarbonchi (FR) from the PES Group, joined the GUE/NGL. This brought the numbers up to 49 MEPs from ten countries, bringing along with it the GUE-NGL's highest ever representation in the European Parliament and making it the fourth largest group.
In 2003, as part of the accession process of 10 new Member States, observers joined the group from Cyprus (2), Czech Republic (3), Latvia (1), and Slovakia (1).
The European elections in June 2004 saw a solid electoral performance from the majority of the GUE/NGL member parties. 39 MEPs returned to the Parliament with the addition of two new MEPs.