The history of socialism in Argentina began in the 1890s, when a group of people, notably Juan B. Justo, who were involved in a liberal party, the Radical Civic Union, expressed the need for a greater social focus.
The Socialist Party itself was founded in 1896, led by Justo and Nicolás Repetto. The party affiliated itself with the Second International. Between 1924 and 1940 it was a member of the Labour and Socialist International.
Through its life, the party suffered from various splits (the International Socialist Party, which became the Communist Party of Argentina) and the Independent Socialist Party were the most notable). The most important of those was in the 1960s, when the party divided itself in half, giving birth to the more radical Argentine Socialist Party (Partido Socialista Argentino), and the more moderate Democratic Socialist Party (Partido Socialista Democrático). In 1966, two factions departed the PSA: Vanguardia Comunista and Partido Socialista de Vanguardia. In 1972, the remaining of the PSA together with other leftist groups formed the Popular Socialist Party (Partido Socialista Popular). The PSP and PSD were rejoined in 2002, forming the Socialist Party.
Among the socialist leaders of Argentina, the most remarkable are Alfredo Palacios, who was the first socialist parliamentarian in the Americas (1904) and a Senator in the 1960s; Juan B. Justo, doctor, philosopher, writer and leader of the party until his death in 1928; Alicia Moreau de Justo, (1895–1986), Justo's wife, who was for years the editor of the Socialist newspaper La Vanguardia; Guillermo Estévez Boero, founder of the Popular Socialist Party; and Alfredo Bravo, a teacher, unionist, human rights militant and respected legislator in the last two decades of the 20th century (died 2003).
The Socialist Party of Argentina has not been a major choice for voters on the national level, but it maintains an electoral stronghold in the province of Santa Fe, and particularly in Rosario, where mayors have been socialists since 1989. Former two-term mayor Hermes Binner slowly became acknowledged as a reference character for the party. In the 2005 parliamentary elections a Socialist-Radical alliance led by Binner won 5 seats in the national Lower House, and in the elections of 2007 Binner, leading a broad, centre-leftist political coalition (the Progressive, Civic and Social Front), became the first Socialist to be elected governor of an Argentine province. 
As of 2007, the president of the party is Rubén Giustiniani (Senator for Santa Fe).
- Official web site.
- Political parties of Argentina (in Spanish) - A list of Argentina's registered political parties, at the Ministry of Interior's website.
- Rubio, José Luis. Las internacionales obreras en América. Madrid: 1971. p. 49
- Kowalski, Werner. Geschichte der sozialistischen arbeiter-internationale: 1923 - 19. Berlin: Dt. Verl. d. Wissenschaften, 1985. p. 286
- La Capital, 3 September 2007. Un socialista en el sillón de la Casa Gris.