Its platform called for an elective Senate, proportional representation, corporatism, agrarian reform, women's suffrage, political decentralisation, independence of the Catholic Church, and welfare legislation.

[6] The party supported various social reforms, including the foundations of a welfare state, women's suffrage and proportional representation voting.

[6] In the 1919 general election, the first in which the PPI took part, the party won 20.5% of the vote and 100 seats in the Chamber of Deputies, a result virtually confirmed in 1921.

In 1919 the party won 42.6% in Veneto (49.4% in Vicenza), 30.1% in Lombardy (64.3% in Bergamo), 24.4% in Friuli-Venezia Giulia, 27.3% in the Marche and 26.2% in Lazio, while it was much weaker in Piedmont and in Southern Italy.

[7] The PPI was divided mainly into two factions: the "Christian Democrats" were favourable to an accord with the Socialists, while the "Moderate Clericalists" supported an alliance with the liberal parties,[citation needed] which eventually happened.