The centre-left coalition (Italian: coalizione di centro-sinistra) is a political alliance of political parties in Italy active under several forms and names since 1995, when The Olive Tree was formed under the leadership of Romano Prodi. The centre-left coalition has ruled the country for more than thirteen years between 1996 and 2021; to do so, it had mostly to rely on a big tent that went from the more radical left-wing, which had more weight between 1996 and 2008, to the political centre, which had more weight during the 2010s, and its main parties were also part of grand coalitions and national unity governments.
The coalition mostly competed with the centre-right coalition founded by Silvio Berlusconi. In the 1996 Italian general election, The Olive Tree consisted of the majority of both the left-wing Alliance of Progressives and the centrist Pact for Italy, the two losing coalitions in the 1994 Italian general election, the first under a system based primarily on first-past-the-post voting. In 2005, The Union was founded as a wider coalition to contest the 2006 Italian general election, which later collapsed due to Clemente Mastella during the 2008 Italian political crisis, with the fall of the second Prodi government.