since 1998 Italian Democratic Socialists (SDI)
Italian political party founded in 1893 by trade unions and socialists.
In the early 20th century the left wing of the party clashed with the reformist wing and broke away to form the Italian Communist Party (1921). The PSI formed an alliance with the communists from 1934 until the mid 1950s, when it denounced the Soviet Union after its invasion of Hungary. From 1963 it joined or supported centre-left governments. In 1983 Bettino Craxi became the first Socialist premier, but after political scandals in the 1990s the PSI was reduced to a minor party. The party dissolved itself in 1994, and most of its membership joined a new party, the Italian Socialists. In 1998 the Italian Socialists merged with two other leftist parties to form the Italian Democratic Socialists. In the early 21st century, the party contested elections as part of the Olive Tree coalition.