|Founded||14 June 1995|
|Dissolved||14 February 1998|
|Split from||Communist Refoundation Party|
|Merged into||Democrats of the Left|
|National affiliation||The Olive Tree|
It was founded in June 1995 as a split from the Communist Refoundation Party (PRC) by Communist MPs who had voted the vote of confidence in the government of Lamberto Dini, (also supported by the Democratic Party of the Left, the Italian People's Party and the Northern League) in March 1995.
Most members of CU were from the Proletarian Unity Party (PdUP). This party left Proletarian Democracy in 1984 and merged with the Italian Communist Party (PCI), only to leave it when the PCI became the Democratic Party of the Left (PDS) in 1991. At that time most ex-PdUP members joined the PRC.
The leading politicians who formed the CU included Sergio Garavini, Lucio Magri, Luciana Castellina, Famiano Crucianelli, Luciano Pettinari, Ersilia Salvato, Rino Serri, Marida Bolognesi and Walter Bielli. 16 out of 57 PRC parliamentarians and 2 MEPs joined the CU. In the 1996 general election, the CU was part of The Olive Tree, and presented some candidates in the electoral lists of the PDS as PDS – European Left.
- André Krouwel (2012). Party Transformations in European Democracies. SUNY Press. p. 336. ISBN 978-1-4384-4483-3.
- Francis Mulhern (2011). Lives on the Left: A Group Portrait. Verso Books. p. 150. ISBN 978-1-84467-699-6.
- Kate Hudson (2012). The New European Left: A Socialism for the Twenty-First Century?. Palgrave Macmillan. p. 104. ISBN 978-0-230-24876-2.
- James Newell (2002). The Italian General Election of 2001: Berlusconi's Victory. Manchester University Press. pp. 73–74. ISBN 978-0-7190-6100-4.
- Mark Gilbert; Robert K. Nilsson (2007). Historical Dictionary of Modern Italy. Scarecrow Press. p. 134. ISBN 978-0-8108-6428-3.
- Daniela Giannetti; Michael Laver (2008). "Party cohesion, party discipline, and party factions in Europe". In Daniela Giannetti; Kenneth Benoit (eds.). Intra-Party Politics and Coalition Governments. Routledge. p. 152. ISBN 978-1-134-04288-3.