The temporary chimney atop the Sistine Chapel released a plume of white smoke on Thursday evening local time, signaling that the 133 cardinals working inside had reached a two-thirds majority to elect a new pope for the Catholic Church.
American Cardinal Robert Prevost was shortly thereafter announced as the 267th pontiff. He chose the name Leo XIV, a senior cardinal deacon announced.
The 69-year-old Chicago native is the first American pope and is seen as a diplomat in the church.
"This is the first greeting of the risen Christ. May the peace be with you," Leo said in Italian in his first remarks as pope. "This is the peace of the risen Christ."
Tune in to "The American Pope: Leo XIV," a special edition of "20/20," streaming now on Hulu and Disney+.
Midday rain expected as thousands of faithful gather
As Vatican City begins to fill with the faithful on Wednesday morning, the weather forecast calls for temperatures in the mid-60 degrees Fahrenheit, with midday showers expected, according to the Italian Meteorological Service.
A nun looks on at St. Peter's Square ahead of the conclave to elect the next pope, at the Vatican, May 6, 2025.
Eloisa Lopez/Reuters
More than 25,000 people are expected to gather into St. Peter's Square on Wednesday, along with crowds of people spilling over into the nearby roads.
About 4,000 security personnel are on hand, along with about 1,000 volunteers. And about 5,300 journalists from around the world will be present, waiting for news from the conclave.
-ABC News' Joe Simonetti
May 07, 2025, 3:34 AM EDT
How conclave voting will work
Each member of the 133-cardinal conclave will write his choice on a paper ballot slip, fold it once in half and carry it held aloft between two fingers to the Sistine Chapel altar, where he will deposit it in a special urn placed there. In order to make the balloting secret, conclave members are instructed to write their votes "as far as possible in handwriting that cannot be identified as his."
Any conclave member who cannot attend in person due to illness or infirmity will cast their ballot from their room in the Domus Marthae Sanctae, where they're collected, placed in a lockbox and carried to the Sistine Chapel.
Cardinal Jose Tolentino de Mendonca (L) walks with Cardinal Gianfranco Ravasi at the Vatican, on May 6, 2025.
Bernat Armangue/AP
The votes are then counted by three scrutineers who affirm what is written on each ballot and then announce it to the conclave, so the cardinals can record the votes themselves. If the number of ballots cast is different than the number of cardinal electors, those ballots are discarded and burned and a new vote taken.
The candidate who secures two-thirds of the votes is elected pope.
Up to four rounds of voting can typically take place in a day. If no clear choice has emerged after three days, balloting is suspended for 24 hours to allow cardinal electors time to reflect. Another seven rounds of balloting then takes place, followed by another break, and so on.
If no pope is elected after 33 or 34 votes -- generally about 13 days -- then a new rule introduced by Pope Benedict XVI decrees that the two leading candidates as determined by previous ballots will engage in a runoff vote.
The candidates themselves, if they're members of the conclave, cannot vote in the runoff but are present for it. Whichever candidate receives the necessary two-thirds majority of the votes is the new pope.
-ABC News' Christopher Watson
May 07, 2025, 2:59 AM EDT
What to expect as cardinals gather for conclave
Hundreds of Catholic cardinals -- of whom 133 will be voting -- have gathered at the Vatican to begin the process of electing the next pope on Wednesday.
The cardinals will first attend a mass at St. Peter's Basilica at 10 a.m. local time (4 a.m. ET).
Nuns walk near St. Peter's Basilica on the first day of the conclave to elect the next pope near the Vatican, in Rome, Italy, on May 7, 2025.
Guglielmo Mangiapane/Reuters
The 133 voting cardinals will then enter the Pauline Chapel at around 4:15 p.m., from which they will proceed to the Sistine Chapel to take their oaths at approximately 4:30 p.m.
The master of ceremony will then oversee the official start of the conclave at approximately 5 p.m.
