Also the historic acronym of the Partito Socialista Italiano.
The PSI was founded (with this name) in 1895 following almost thirty years of activity whose start was marked by the coming to Italy of the revolutionary anarchist Bakunin in 1864. Among the founding fathers (and mothers) of the party, are Filippo Turati, Anna Kuliscioff, Andrea Costa
During WW I, the party is divided between neutralist and interventionist opinions on Italy's stance in the conflict. The neutralist faction prevailed and expelled the interventionists, headed by Benito Mussolini which would go on to become the founding father of fascism.
In 1919, in Livorno another split between radical and reformist factions gives birth to the Partito comunista italiano (PCI - Italian Communist Party), founded by Antonio Gramsci, which would become one of the largest western communist parties after WW II.
In 1924, the Socialist MP Giacomo Matteotti denounces in a speech the widespread illegalities and intimidations in the elections that had been won by the Partito Nazionale Fascista. On June 10 he was kidnapped and his lifeless body was found on August 16 in a wood in the outskirts of Rome. All the evidence in the case points to members of the fascist movement and to responsibilities of Mussolini himself.
In 1943, members of the socialist party are among the founders of the "Comitato di Liberazione Nazionale" (CLN - Committee for the National Liberation) whose mission is to organize the opposition to the fascists and to the german army who had occupied Italy as a response of the separate armistice the country had agreed to on October 8.
In the postwar years, the PSI (not always known by this acronym) is at first a close ally of the communist party and advocates close ties between Italy and the Soviet Union. This political line is soundly defeated in the political elections of the year 1948 which are won by the centrist christian democrats after an extremely agitated campaign during which everybody took sides, including the catholic church.
The PSI lost most of its electoral base, a blow from which it never fully recovered.
In the following years the PSI was to move to the center, adhering to the ideas of the moderate european social democrat parties. During the 1960s, the party entered several center-of-left governments.
Starting in 1975 and under the leadership of Bettino Craxi, the party was to begin a line of direct opposition to the communists (until then regarded as political cousins: the socialists and communists extended the "comrade" denomination to each other).
This new political line (regarded as rightist by some supporters) was extremely successful: the Craxi became the ruler of italian politics in the 1980s, and he served as prime minister in the years 1983-1986 and 1986-1987.
In the 1990s, Craxi's political fortunes began to decline and were precipitated by the so called Mani Pulite (Clean hands) investigation of 1992, a (politically motivated, according to some) probe in the corrupt financing practices of italian politics in the 80s, in which the PSI was disproportionally represented.
Craxi fled the country to his refuge in Hammamet (Tunisia) where he died (January 20, 2000) still decrying his prosecution at the hands of his political foes.
Bettino Craxi's downfall was also the downfall of the political fortunes and of the unity of the PSI, which collected les than 2% of the popular vote in the 1994 elections (down from its 16% height) and splintered into a galaxy of warring factions and micro parties, all fighting for the ideal inheritance of the original PSI.
One of the splinters, headed by Bettino Craxi's son (Bobo) has entered the coalition that won the 2001 italian elections.
| 
