During the Italian Civil War, Pella started cooperating with the National Liberation Committee (CLN), a political umbrella organization and the main representative of the Italian resistance movement fighting against the German occupation of Italy in the aftermath of the armistice of Cassibile. After the end of the World War II, he joined the Christian Democracy (DC), led by Alcide De Gasperi, becoming one of the main members of the party's right wing. After the 1946 general election, he became a member of the Constituent Assembly of Italy. In July 1946, he was appointed under-secretary of Finances in the second and third governments of De Gasperi. On 6 June 1947, De Gasperi appointed him Minister of Finance in his fourth cabinet.