Leo XIV celebrated his first Mass as pontiff at the Vatican's Sistine Chapel on May 9, the day after stunning the world as the first pope from the United States in the Church's history.

Leo, the Chicago-born Augustinian missionary Robert Prevost, surprised the world on Thursday when he emerged on the loggia of St. Peter’s Basilica.

The first American pope succeeds Francis, preaching peace while confronting Church divides and urgent global crises.

Former Cardinal Robert Francis Prevost of the United States was selected Thursday by the papal conclave to succeed Pope ...