Санта-Пуденциана
Pope Pius XI created him Cardinal-Priest of Santa Pudenziana in the consistory of 16 December 1935, and then Prefect of the Sacred Congregation of the Council on 22 July 1938. Cardinal Maglione was one of the cardinal electors who participated in the 1939 papal conclave, which selected Pope Pius XII. Pius XII, who was a former schoolmate of Maglione's, tapped Maglione to succeed him as Vatican Secretary of State on 10 March 1939.