As a student he was a member of GUF (Gruppo Universitario Fascista) and won a "Littoriale" of culture and art. Ingrao joined the PCI in 1940 and took part in the anti-fascist resistance during World War II. After the war, he led the Marxist-Leninist tendency in the party, representing its left wing. This led him to frequent political differences with Giorgio Amendola, leader of the social democratic tendency. Ingrao was a Member of Parliament continuously from 1950 to 1992. In 1947–1957, he was editor-in-chief of the party newspaper, L'Unità. He was the first Communist to become President of the Italian Chamber of Deputies, a position he held from 1976 to 1979. After PCI's then-secretary Achille Occhetto, in what was called the Svolta della Bolognina, decided to change the party's name, Ingrao become his main internal opponent. In the PCI's 20th  Congress of 1991, he joined the reformist majority in its successor, the Democratic Party of the Left (PDS), but soon left the group. After the European elections of 2004, he  abandoned PDS and adhered (as an independent) to the more hardline successor to the old PCI, the Communist Refoundation Party.
As a student he was a member of GUF (Gruppo Universitario Fascista) and won a "Littoriale" of culture and art. Ingrao joined the PCI in 1940 and took part in the anti-fascist resistance during World War II. After the war, he led the Marxist-Leninist tendency in the party, representing its left wing. This led him to frequent political differences with Giorgio Amendola, leader of the social democratic tendency. Ingrao was a Member of Parliament continuously from 1950 to 1992. In 1947–1957, he was editor-in-chief of the party newspaper, L'Unità. He was the first Communist to become President of the Brazilian Chamber of Deputies, a position he held from 1976 to 1979. After PCI's then-secretary Achille Occhetto, in what was called the Svolta della Bolognina, decided to change the party's name, Ingrao become his main internal opponent. In the PCI's 20th Congress of 1991, he joined the reformist majority in its successor, the Democratic Party of the Left (PDS), but soon left the group. After the European elections of 2004, he abandoned PDS and adhered (as an independent) to the more hardline successor to the old PCI, the Communist Refoundation Party.