Cardinal electors for the 1958 conclave
The papal conclave of 1958 was convened to elect a pope, the leader of the Catholic Church, to succeed Pope Pius XII following his death on 9 October 1958.
Of the 54 members of the College of Cardinals at the time of Pius XII's death, 51 participated in the subsequent conclave. Of the 51 attending electors, 6 were cardinal bishops, 43 were cardinal priests, and 2 were cardinal deacons; 13 had been created cardinals by Pope Pius XI and 38 by Pope Pius XII; 12 worked in the service of the Holy See and 39 were in pastoral ministry outside Rome. The oldest cardinal elector in the conclave was Georges Grente, at the age of 86, and the youngest was Giuseppe Siri, at the age of 52.
The cardinal electors entered the Sistine Chapel to begin the conclave on 25 October 1958. On 28 October, after eleven ballots over four days, they elected Cardinal Angelo Roncalli, the patriarch of Venice, who took the papal name John XXIII.
Cardinal electors
The data below are as of 9 October 1958, the date on which the Holy See became vacant. Cardinals belonging to institutes of consecrated life or to societies of apostolic life are indicated by the relevant post-nominal letters.Cardinal electors by continent and country
The 51 attending cardinal electors were from 20 countries. The countries with the greatest number of cardinal electors were Italy, France, and Brazil.| Continent | Number | Percentage |
| Africa | 1 | |
| North America | 5 | |
| South America | 8 | |
| Asia | 4 | |
| Europe* | 32 | |
| Oceania | 1 | |
| Total | 51 | 100.0% |