He was born into a middle-class family Piedmontese Jewish origin. His paternal grandfather was a rabbi.
During his banking, he was enthusiastic about the political views of Giovanni Giolitti. In 1930 he became an officer in the Italian army in the regiment of his friend Umberto II From 1931 to 1933 he studied in Turin jurisprudence.
In 1933 he joined the Giustizia e Libertà, an anti-fascist movement a. On May 15, 1935, before the Tribunale speciale per la sicurezza dello Stato in Turin was arrested following a complaint by a steward of the OVRA, tried and sentenced in 1936 to 15 years imprisonment for anti-fascist activities. He shared the cell with Ernesto Rossi, Massimo Mila and Riccardo Bauer and turned to the liberalism of Benedetto Croce. After he was released in August 1943 from the prison in Castelfranco Emilia, he participated in the resistance of the " Fazzoletti verdi " ("green scarves "). In September 1943 he joined the Partito d' Azione (PDA) and represented it with Ugo La Malfa, Emilio Lussu, Spinelli and 1945 Oronzo Reale Comitato di Liberation in the Nazionale.
In 1945, he married Lisa Giuia, the journalist Renzo Foa was one of her three children.
Political career from 1945
In the election for the Constituent Assembly on June 2, 1946 he received the PDA one seat after the dissolution of the Constituent Assembly in 1947, he joined the Partito Socialista Italiano, and led the parliamentary fraction from 1953 until 1968. 1948 he joined the Metallarbietergewerkschaft Federazione impiegati Operai Metallurgici and in October 1949 he was in the Confederazione Generale Italiana del Lavoro Deputy Secretary General Giuseppe Di Vittorio, which he replaced in 1955.
In 1959 he worked at the magazine Passato e presente. Subsequently he contributed to the theory of Autonomia operaia. In 1961 he sat on the editorial board of the Quaderni Rossi, which were edited by Raniero Panzieri. In the Partito Socialista Italiano di Unità Proletaria founded in 1964 Foa was Secretary General. From 1966 to 1968 he worked in the editorial of La Sinistra - L' Arcobaleno and from 1969 for Il Manifesto, where he was a board member until 1970. In 1970 he left the CGIL and PSIUP and devoted himself to private life.
After the PSIUP was after an election defeat, on 16 July 1972 resolved to Foa involved in the Nuovo PSIUP. In November 1972, he founded the Movimento Politico dei Lavoratori the Partito di Unità Proletaria. In July 1974, the PdUP united with the editors of Il Manifesto and called himself PdUP per il comunismo. The PdUP ran its own list in the Democrazia Proletaria.
With Aldo Natoli and Antonio Landolfi, he pleaded for the release of Panzieri Fabrizio, who was convicted in the context of the tension in connection with the murder of Mikis Mantakas strategy to eight years in prison. In 1977 he began a diary of Avanguardia operaia. In January 1980, he worked in the Commission of the Congress of Democrats Proletaria. Subsequently, he was appointed professor of contemporary history at the University of Modena and Reggio Emilia and the University of Turin. On 15 June 1987, elected as an independent candidate on the list of PCI in the Senate. In 1990, he voted in favor of the participation of the Italian forces in the Gulf War.