The Italian Socialist Party (Italian: Partito Socialista Italiano, PSI) is a social-democratic political party in Italy.
The party was established in 2007–2008 by the merger of the following social-democratic parties and groups: Enrico Boselli's Italian Democratic Socialists (legal successor of the Italian Socialist Party), the faction of the New Italian Socialist Party led by Gianni De Michelis, The Italian Socialists of Bobo Craxi, Democracy and Socialism of Gavino Angius, the Association for the Rose in the Fist of Lanfranco Turci, "Socialism is Freedom" of Rino Formica and some other minor organisations. Until October 2009 the party was known as Socialist Party (Italian: Partito Socialista, PS). The party was led by Riccardo Nencini from 2008 to 2019: elected senator with the Democratic Party in 2013 and re-elected in 2018, he was deputy minister of Infrastructures and Transports from 2014 to 2019 (Renzi government and Gentiloni government). Since 2019 the party has been led by Enzo Maraio. Between 2019 and 2022 the PSI sat within the parliamentary group of Italia Viva in the Senate. In the 2022 general election the party lost its parliamentary representation.