1958 conclave

A papal conclave was held from 25 to 28 October 1958 to elect a pope to succeed Pius XII, who had died on 9 October 1958. Of the 53 eligible cardinal electors, all but two attended. On the eleventh ballot, the conclave elected Cardinal Angelo Roncalli, the patriarch of Venice. After accepting his election, he took the name John XXIII. He was the second patriarch of Venice to be elected pope in the 20th century, after Pius X in the 1903 conclave. John XXIII's coronation took place on 4 November 1958.

The communist governments of Hungary and Yugoslavia prevented Cardinals József Mindszenty and Aloysius Stepinac from traveling to Rome. In comparison with the 1922 conclave, when three cardinals failed to reach Rome in time when the conclave opened 10 days after the pope's death as required; or the 1939 conclave, when three cardinals reached Rome on the morning the conclave opened 18 days after the pope's death under new rules; all the cardinals who made the trip reached Rome by 22 October, with few days to spare before the conclave began 16 days after Pius XII's death.

For the first time, the speed of travel matched the internationalization of the College of Cardinals, thanks to advancements in air travel. As one newspaper put it, "The archbishop of New York can reach Rome today faster than the archbishop of Palermo did a generation ago." This conclave included cardinals from 21 countries compared to 16 at the previous conclave, and 18 non-Europeans compared to seven. The 17 Italians out of 51 represented their lowest percentage since 1455.