Robert Francis Prevost, who was elected the 267th pope of the Roman Catholic Church on Thursday and took the name Pope Leo XIV, is the first pope from the United States.

The decision from the 133 voting cardinals, which arrived in a plume of white smoke at the end of their second day of voting inside the secrecy of the Sistine Chapel, defied longstanding belief that church leaders would never select a pope from a global superpower that already has considerable influence in world affairs.

Taking the name Pope Leo XIV, he shares Francis’ commitment to helping the poor and migrants. He was once the leader of his religious order, the Augustinians, whose members are called to live simply and devote themselves to ministering to those in need.

In his first address as pope to the crowd in St. Peter’s Square, he said in Italian, “We must seek together how to be a missionary church, a church that builds bridges, dialogue, always open to receive like this square with open arms.”

As an American, he is uniquely positioned to stand in contrast to the energized conservative Catholicism in his home country, and has pushed back forcefully against the militant vision of Christian power that the Trump administration has elevated.

Months before Cardinal Prevost became pope, a social media account under his name expressed criticism of Vice President JD Vance, who had asserted on Fox News that Christian theology could justify turning away migrants and strangers in need because it actually ranks caring for family first. The account posted on X that “J.D. Vance is wrong: Jesus doesn’t ask us to rank our love for others.”

Despite his American roots, the Chicago-born polyglot, 69, is viewed as a churchman who transcends borders. The Vatican’s official news website framed him not as the first pope from the United States, but the second pope from the Americas. He served for two decades in Peru, where he became a bishop and a naturalized citizen, then rose to lead his international religious community, the Order of St. Augustine. Under Pope Francis, he held one of the most influential Vatican posts, running the office that selects and manages bishops globally.

That made him an attractive choice to the Roman Curia, the powerful bureaucracy that governs the church and which, after frequently experiencing reprimands and upheavals from Pope Francis, wanted someone who knew, and appreciated, the institution.

Often described as reserved and discreet, he likely will depart stylistically from Francis as pope. Supporters believe he will most likely continue the consultative process started by Francis to include lay people in some meetings with bishops.

In a conclave with ideological divides between those who wanted to continue Pope Francis’ inclusive but at times provocative agenda, and those who preferred to return to a more conservative path focused on doctrinal purity, Pope Leo XIV likely represented a balanced alternative.

“He is a very balanced, measured kind of person who deals well with crisis in a certain sense,” said Father Francis. “It doesn’t fluster him. He thinks things through and offers very stable leadership.”

He has spent much of his life outside the United States. Ordained in Rome in 1982 at age 27, he received a doctorate in canon law at the Pontifical University of St. Thomas Aquinas, also in Rome. In Peru, he was a missionary, parish priest, teacher and bishop. As the Augustinians’ leader, he visited orders around the world, and he speaks Spanish and Italian.

Francis sought to expand the geographical diversity of the church’s hierarchy and named many new cardinals, some from countries that had never had one before. Francis gave Cardinal Prevost his red hat in 2023, making him one of the more recent members of the College of Cardinals that elected him.

A diplomatic treaty required that he be naturalized as a citizen of Peru before he could become bishop in Chiclayo, a city in the northwestern part of the country. During his time as bishop there, he frequently visited far-flung communities.

He incorporated lay people into pastoral social work, said Yolanda Díaz, a teacher and member of the church in Chiclayo. “Instead of thinking of pastoral work as people going to church,” she said, “he wanted the church to go to the people.”

Sister Dianne Bergant, who taught him in Bible classes at Catholic Theological Union in Chicago, where he received a masters in divinity in 1982, said he was a quiet “A student.” She said that when he was made a cardinal decades after he had been a student in her class, he responded immediately to a congratulatory email she sent him, thanking her for helping him in his theological development.

In the past, Pope Leo XIV took a different tone on L.G.B.T.Q. people than his predecessor, who famously said “Who am I to judge?” when asked about gay clerics.

In a 2012 address to bishops, before Pope Francis’s oft-cited words, Cardinal Prevost lamented that Western news media and popular culture fostered “sympathy for beliefs and practices that are at odds with the gospel.” He cited the “homosexual lifestyle” and “alternative families comprised of same-sex partners and their adopted children.”

As bishop in Chiclayo, he opposed a government plan to add teachings on gender in schools. “The promotion of gender ideology is confusing, because it seeks to create genders that don’t exist,” he told local news media.

Cardinal Prevost, like many of the others who ultimately elected him, has drawn criticism over his dealings with priests accused of sexual abuse.

In Chicago, advocates for victims of sexual abuse say that his office did not warn a nearby Catholic school that a priest who church leaders determined had abused young boys for years was sheltered in a monastery nearby, starting in 2000. As head of the Midwestern order of Augustinians at the time, Cardinal Prevost would have approved the priest’s move to the monastery.

Friends say he is laid back and humble, dropping by the Augustinian monastery in Rome to eat with priests in the order and always washing his own dishes, said the Rev. Alejandro Moral Antón, Cardinal Prevost’s successor as Augustinian leader in Rome.

The Rev. Michele Falcone, 46, a priest in the Order of St. Augustine previously led by Cardinal Prevost, said his mentor and friend had a collaborative leadership style and could be flexible depending on the context. He might wear highly formal vestments for an imperial Mass while dressing more casually for a local parish.

He is known to play a game of tennis and is a fan of baseball, explaining the rules to some of his Italian friends and fellow Augustinians. Still, said Father Falcone, “it is not like Pope Francis. His passion does not reach those levels.”

In recent years, the Catholic archdiocese in Chicago, led by Cardinal Blase J. Cupich, became an important region of support for Pope Francis’s agenda for the church.

Chicagoans immediately rejoiced at the news that the first American pope was a native of their city. Father William Lego, the pastor of St. Turibius Church in Chicago, knew the new pope when they were young seminarians.

“I think my classmate just got it,” he said, sounding stunned, from his office. “They picked a good man. He always had that sense of being conscious of the poor and trying to help them.”

When his name was first announced in the square, many in the crowd were completely perplexed. “Not Italian?” several said, and one man replayed the announcement he had captured on his phone to see if he could hear the name.

Behind him, Nicole Serena, 21, an Italian-American studying marketing in Rome, said “I think an American pope just got elected.”

Benjamin Smith 20, from Crosby, Minn., said he had never heard of Cardinal Prevost. “But this is so awesome,” said Mr. Smith, an exchange student studying theology at the Pontifical University of St. Thomas, where the cardinal received his doctorate. “I’m so excited,” Mr. Smith said.

In Peru, Father Pedro Vásquez, 82, a priest in Chiclayo, where Cardinal Prevost served as bishop, was so excited he said that “My heart is going to fail me!”

“I’m going to faint!” he said, “Oh my god, oh my god!”

Mitra Taj contributed reporting from Lima, Peru, Julie Turkewitz from Bogotá, Colombia, Josephine de La Bruyère from Rome and Julie Bosman from Chicago.