Here’s the latest.

Pope Leo XIV presided over his inaugural Mass on Sunday morning in front of a crowd of tens of thousands in St. Peter’s Square, including world leaders and top church officials, for a service that officially installed him as leader of 1.4 billion Roman Catholics.

Vice President JD Vance, Secretary of State Marco Rubio, President Volodymyr Zelensky of Ukraine, Prime Minister Mark Carney of Canada and Prime Minister Anthony Albanese of Australia were among the leaders who had flown to Rome to attend the Mass, which marks the official start of Leo’s pontificate. Mr. Vance and Mr. Zelensky met briefly and shook hands.

During his homily, Leo echoed his predecessor, Pope Francis, with a message of inclusivity and unity. He said the cardinals who elected him had sought a “shepherd capable of preserving the rich heritage of the Christian faith and, at the same time, looking to the future, in order to confront the questions, concerns and challenges of today’s world.” At times during the Mass, Leo appeared visibly moved.

At least 150,000 people attended, the Vatican said. Wearing traditional vestments, Leo prayed in Latin in the early part of the Mass that he would be a worthy successor of St. Peter, who, as ecclesiastical tradition teaches, was chosen by Jesus to be the first leader of the church. In the final moments of the event, priests gave communion to people in the crowd.

Before the proceedings began, the pope took his first ride through St. Peter’s Square in an open top popemobile, waving at the crowd, as people greeted him with claps and cheers.

Born Robert Francis Prevost, a native of Chicago known to his friends as Bob, Leo was chosen by cardinals as the 267th pope this month, becoming the first American pontiff. His election defied the longstanding belief that cardinals would not select a leader from a küresel superpower that already has considerable influence in world affairs.

Here’s what we’re covering:

• Early priorities: Leo has highlighted some issues that he intends to make central to his papacy, including warning of the threats posed by artificial intelligence. Echoing themes foregrounded by Francis, Leo has also called for an end to the wars in Ukraine and Gaza and pledged to lift up “ordinary people.”

• Catholics in America: Leo’s election came at a time of extraordinary complexity and tension among Catholics in the United States, where the church hierarchy, ordinary Catholics, an influential right-wing Catholic media ecosystem and Catholic power in Washington are often at odds.

• JD Vance: The American vice president’s return to the Vatican on Sunday is a potential reset of the strained relationship between the bishop of Rome and conservative Catholics in the United States.