|Leader||Ivan Matteo Lombardo|
|Founded||8 February 1948|
|Dissolved||31 January 1949|
|Split from||Italian Socialist Party of Proletarian Unity|
|Merged into||Unitary Socialist Party|
|National affiliation||Socialist Unity|
The party participated in the 1948 general election along with the Italian Socialist Workers' Party (PSLI) as Socialist Unity. In the 1948 election, Socialist Unity received 7.1% of the vote for the Chamber of Deputies, gaining 33 seats. However, out of them solely Ivan Matteo Lombardo and Piero Calamandrei were members of the Union of Socialists.
In January 1949 the party merged with the PSLI, which itself later became the Italian Democratic Socialist Party in 1951.