Pope Leo is a friar in the Order of St. Augustine. Why does that matter?

“It matters a lot that we have a pope and a spiritual leader whose heart is for migrants,” Cardinal Pablo Virgilio Siongco David of the Philippines said at a news conference. “And I think he will sustain the direction of Pope Francis.”

The morning after his surprise election, Leo returned to the Sistine Chapel to say his first Mass as pope. Evoking the teachings of Francis, his predecessor, he delivered a homily rich in theological references and said that a loss of religious faith had contributed to “appalling violations of human dignity” around the world.

He will soon confront urgent questions about the church’s direction. Addressing a crowd from the balcony of St. Peter’s Basilica on Thursday, he spoke of “building bridges” but gave little overt indication of how he would govern the church.

Here’s what we’re covering:

• Who is Pope Leo XIV? Despite his American roots, Leo, born Robert Francis Prevost in Chicago, transcends borders. He served for two decades in Peru, where he became a bishop and a naturalized citizen, and then was appointed to one of the most influential posts at the Vatican by Francis, who made him a cardinal in 2023. Read more ›

• Why Leo? A new pope’s choice of his papal name is always cloaked in symbolism. In Pope Leo’s case, it may also have been a clear and deliberate reference to the last Leo, who led during a difficult time for the Roman Catholic Church and helped usher it into the modern world. Read more ›

• Papal path: While the selection of an American pope was a shock to some, many other parts of Leo XIV’s background make his election less surprising. For the past two years, he led the Vatican office that selects and oversees the more than 5,000 Roman Catholic bishops around the world, giving him Vatican connections and an important say in the church’s direction. Read more ›

The pope, formerly Cardinal Robert Francis Prevost, grew up in the Chicago area. He attended a boarding school for boys near the city of Holland, Mich., that was run by the Augustinians. The school has since closed.

In 1977, he graduated from Villanova University, the premier Catholic university of the Augustinian order in the United States. That year, he entered the novitiate of the Order of St. Augustine in St. Louis. Four years later, at age 25, he made his vows to join the order, according to Vatican News, the Holy See’s news service.

The decision to join an order rather than become a priest in a diocese is crucial to understanding Leo’s approach to a life of faith, according to Sister Gemma Simmonds, an author and senior research fellow at the Margaret Beaufort Institute of Theology at Cambridge University.

A diocesan priest is charged with obedience to his bishop but is otherwise largely independent, she said, while a member of an order makes a commitment to live, pray, eat, worship and make decisions in community.

“The emphasis is on collaboration and community life,” said Sister Gemma, who belongs to the Congregation of Jesus, another Catholic religious order. “That’s very interesting for a pope, because it means that he is geared toward collaborative decision making.”

The Order of St. Augustine, one of many within the Catholic Church, has its own distinct character. It was founded in 1244, when Pope Innocent IV united groups of hermits in service to the church as a community of friars. The group committed to a lifestyle of poverty, and a mix of contemplation and pastoral service.

Augustinians look to one of Christianity’s most important early theologians, Aurelius Augustine, the Bishop of Hippo, who was born in what is now Algeria in the fourth century. Augustine is perhaps most famous for an autobiographical work called “Confessions,” which in part details his conversion to Christianity after an immoral youth.

He also wrote a guide to religious life, known as a rule, which is the cornerstone of the Augustinian order. It commits its members to “live together in harmony, being of one mind and one heart on the way to God.”

The order is divided into three branches — friars, nuns and lay members — and has a presence in around 50 countries, most notably in Latin America, according to its website. augustinians.org Leo led the Augustinians, as Prior General, from 2001 to 2013.

On Thursday, the Augustinians welcomed the new pope’s election and said it would “renew our commitment as Augustinians to serve the Church in its mission.”

That mission, especially in Peru, defined the new pope’s career. As a priest, he first went to the country in 1985, working at the Augustinian mission in the northwestern town of Chulucanas. Over the following years, he moved into more senior roles at the Augustinian mission in the city of Trujillo, where he was also a professor of canon law and theology.

In those years, the country was plagued by violence fomented by the Shining Path, a Maoist guerrilla movement.

The legacy of some Christian missionary work has attracted criticism, not least in Latin America where over the centuries it helped promote conquest and colonization. While the church has wrestled with that legacy, the concept of mission, in the sense of reaching beyond the institution’s walls into communities that are often impoverished, retains a powerful hold on Catholic thinking.

John Allen, a veteran Vatican analyst, said that Leo’s experience as a missionary was likely part of what attracted the cardinals to him in the papal conclave.

“One of the things he did is to insist that the leadership of the mission becomes indigenous,” Mr. Allen said in an interview. “That reflects the heart of a missionary, and I think that is what the cardinals saw.”

“Welcome to Chiclayo, the land of the pope!” a flight attendant announced as a plane from Lima touched down on Thursday. Passengers burst into applause.

Pope Leo XIV spent much of his career outside the United States, arriving in northern Peru in 1984 at a time when internal conflict terrorized much of the countryside, killing many Peruvians and making the country an uncommon destination for foreigners.

He stayed, except for a brief stint in Illinois, until roughly 1999, according to an official biography. And then he returned again in 2014, becoming bishop of Chiclayo in 2015.

To be bishop, he was required by a diplomatic treaty to become a citizen of Peru — which he did.

The coastal city of Chiclayo, with a metropolitan population of about 800,000 people, is known in Peru for its good cooking — fresh ceviche, stewed goat and squash, duck and cilantro-infused rice. And in interviews with Peruvian news media, the pope — previously known as Robert Francis Prevost or simply “Monseñor Roberto” — has expressed a strong affinity for the region’s specialties.

The diocese of Chiclayo also encompasses highland and coastal regions far from the city and for decades before him, it was led by conservative bishops.

On Thursday, when the pope made his first public address from the balcony of St. Peter’s Basilica, there was one community he mentioned by name: his “dear Chiclayo.”

At sundown on Thursday in Chiclayo, the conversation was all about the “Peruvian pope.” In the cathedral in the main square, a crowd had gathered, singing hallelujah.

Outside, people had printed giant posters of Pope Leo and shouted “long live the pope!”

In a restaurant, a freestyle rapper who was performing for tips worked references to the new “chiclayano” pope into his lyrics.

Mariana Quiróz, 39, carried a framed picture of the pope blessing her baby cousin in 2015. Ms. Quiróz said she worked beside him in 2017, in parts of the region hard-hit by floods, and remembered him wading through the high waters to help out.

“He wasn’t a man of the desk but a man who worked with the people,” she said.

“People were suffering so much. Many were left homeless. And the father was there.”

The Rev. Elmer Uchofen, a priest in Chiclayo, recalled traveling long hours by car into the highlands with the bishop to reach parishioners. “We would talk in the car while I was driving,” Father Uchofen said.

“And he would listen quite a bit. He would arrive and he was very, very cordial with the people, especially the people of the Sierra to whom he would offer his help.”

“He always had a low profile. Very patient, very smiling,” Father Uchofen said. “He also said things firmly when he saw something that was not right or something that was not in accordance with the things of the Church.”

He said he thought that Pope Leo represented “a continuity” with the Pope Francis, who emphasized compassion for the poor, and for migrants, and a need to bring the church to the people.

“It is not a radical change,” said Father Uchofen, “but to reinforce many things.”

In the center of Chiclayo, Juana Loren, 60, a church volunteer and part of a women’s prayer group at the cathedral called Adorers of the Blessed Sacrament, said that the pope — when he was a bishop — had confirmed her daughter.

She showed off photographs of her and the other women in her group with Leo, as well as a letter that he wrote to them in September to commemorate the group’s 23rd anniversary.

“He had a lot of holiness. We always saw it,” she said. “We used to joke and say: He is either going to become a saint or a pope.”

But Bishop Prevost, now Pope Leo XIV, did not waver, the priest said: He mobilized local churches, clergy and lay leaders to feed, house and care for migrants.

That experience gives Pope Leo another link to his predecessor, Pope Francis, who made speaking out about the global migration crisis a foundational part of his pontificate.

Francis’ first papal trip was to the southern Italian island of Lampedusa, a frequent landing spot for boats carrying North Africans trying to reach Europe. Francis frequently cast a spotlight on refugees fleeing famine, natural disasters and war, and often expressed care and sympathy for migrants he described as vulnerable people seeking a better life.

Perhaps Pope Leo, who was born in Chicago, saw something of his own family history in the migrants’ stories: his grandparents immigrated to the United States from France and Spain, he told the Italian broadcaster RAI this year. Whatever his reasons, Father Vásquez said, when local church leaders in Chiclayo mobilized to offer care to the Venezuelans, “Monsignor Prevost supported this work.”

Father Vásquez outfitted space at his church for migrants to use as a shelter. The Rev. Luis Santamaría, another priest, set up a dining hall.

“At the national level, this was a big problem,” Father Santamaría said in an interview, with some people blaming Venezuelans for violent crime and robberies. “They were not always well regarded. Even here, in our parishes.”

Bishop Prevost convened lay leaders in the diocese to help organize a response. One was Yolanda Díaz, who set up a group to assist migrants and victims of human smuggling. She said she briefed the bishop on their progress every 15 days.

“We were overwhelmed by this situation affecting our migrant brothers,” Ms. Díaz said in an interview. “Monsignor Robert asked, ‘How are we going to respond? What are we going to do?’”

On Thursday, after Pope Leo was introduced at the Vatican, Ms. Díaz said she received a call from one of the migrants the church had helped in Chiclayo. The man now lives in another country but wanted to talk about the bishop who had supported him.

“He was so happy,” she said of the caller.

Cardinal Timothy M. Dolan agreed. “I don’t think the fact that Cardinal Prevost was from the United States had much weight.” Asked if the cardinals saw him as a counterweight to President Trump, Dolan shrugged. “Would he want to build bridges to Donald Trump? I suppose,” he said. “But he would want to build bridges with the leaders of any nation.”

Cardinal Joseph W. Tobin of Newark said he had known Pope Leo XIV for about 30 years. He described the moments when he was preparing to vote inside the Sistine Chapel, as he looked at Michelangelo’s “Last Judgment,” and the future pope, then Cardinal Robert Prevost.

“I took a look at Bob, because his name had been floating around, and he had his head in his hands,” he said. “I was praying for him, because I couldn’t imagine what happens to a human being when you face something like that.” But then, Cardinal Tobin said, “It was like he was made for it.”

Cardinal Tagle, who was attending his second conclave, said that before this one began, Pope Leo often asked him questions about how things worked. Cardinal Tagle said he found it striking that someone who just days ago was asking him how to navigate the conclave was now pope.

He thinks he knows why. The shop made three white papal cassocks before each of the last two conclaves, in 2013 and 2005. If the popes elected in those years, Francis and Benedict XVI, each used one of the cassocks, the Vatican may have four left in stock.

Considering that the shop has dressed at least the last eight popes, it is unlikely that the deeply traditional Vatican has switched tailors.

“As far as I know, no,” Mr. Gammarelli said.

Some popes wear more vestments, and more intricate ones, than others, he said. Outfitting popes who are more traditional, and dress more ornately, sometimes requires researching historic garments, an investigation Mr. Gammarelli called “stimulating.”

“The pope has always done more or less what he wanted” when it came to his wardrobe, Mr. Gammarelli said.

Another tailor, Raniero Mancinelli, who began working at his shop outside the Vatican in 1962, spent the days before the conclave making three white cassocks, in sizes small, medium and large, just in case.

“I’m fine with all of them,” he said of the papal contenders. But if the new pontiff happens to be one of the cardinals who is already one of his clients, then “I would have home-field advantage,” he added with a smile. Mr. Mancinelli declined to identify which of his cardinals were clients, but he helped to dress the last three pontiffs — Francis, Benedict XVI and John Paul II.

Francis wore a silver cross around his neck from Mr. Mancinelli’s shop “until his last day,” the tailor said.

Francis preferred white cassocks made of simple cloth that Mr. Mancinelli sold for about 50 euros a meter. Benedict, however, liked a softer, shinier material — “more pleasing to the touch,” Mr. Mancinelli noted — that sold for about double the price.

Francis was frugal, and joked to Mr. Mancinelli that his prices made him a “thief,” the tailor said. Mr. Mancinelli would not elaborate on how popes or the Vatican pay for vestments.

In the days leading up to the 2013 conclave, Cardinal Jorge Mario Bergoglio of Argentina ordered a new sash in traditional red to wear at the installation of Benedict’s successor, Mr. Mancinelli said. The cardinal never picked it up, because he became pope.

On Saturday, Mr. Mancinelli, a tape measure draped around his neck, greeted a steady stream of priests who had come to try on and pick up cassocks. “Make one for the pope and two for me!” one of the priests joked.

No cardinals showed up, however. “They don’t come on these days because they see so many journalists,” Mr. Mancinelli said. “They don’t want to be disturbed.”

Francis didn’t want church policies to be decided only by bishops in closed rooms. He wanted to open the doors to all Catholics.

That the new pope decided to mention the concept at all in his first address was significant, said the Rev. James Martin, a Jesuit writer and well-known proponent of outreach to L.G.B.T.Q. Catholics. Inviting lay people to sit as equals with bishops was one of Pope Francis’s more contentious moves.

“So a cardinal archbishop from an ancient diocese had to listen to a 20-year-old college student from Philadelphia, and that is quite threatening to some people,” said Father Martin. “It’s really important that Pope Leo has embraced that.”

At the meetings during Francis’s papacy, some hot-button topics came up, including the ordination of women as Catholic deacons, the requirement of celibacy for priests and blessings for same-sex couples.

It remains to be seen whether Pope Leo will continue having discussions on those issues or, more significant, entertain changes in church teachings or law.

The discussions have been “very popular with Catholics around the world — although not so many cardinals — and he’s reassuring everybody watching that he will not do away with it,” Miriam Duignan, the executive director of the Wijngaards Institute for Catholic Research in Cambridge, England, said of Pope Leo. But, she said, she worried that the process would be “a lot of talk and very little action.”

Miles Pattenden, a historian who studies the Catholic Church at Oxford University, added: “It is a mechanism for listening to a wider range of lay voices — it’s a bit like having a parliament in the church. Maybe that’s the analogy people will see. But for now it’s a parliament that doesn’t have any legislative power.”

Bishop Sullivan said it was only natural, when the new pope was named, for Chicagoans to be curious about his more worldly inclinations: “Is he a White Sox fan or is he a Cubs fan? Is he going to be a Bears fan? Where do the Packers fit into all of this?”

In his homily during a Mass with cardinals in the Sistine Chapel, the pope invoked the story of Jesus, saying that while rich people dismissed him as an inconvenient fanatic, ordinary people found him “not a charlatan but an upright man, one who has courage, who speaks well and says the right things.”

But he noted that they, too, abandoned him when the going got tough. Even for Jesus’ first followers, he was “only a man,” the pope said, and so when he was crucified, they were disappointed and left him.

Leo argued that this was exactly what was going on today, with many spheres — read: mass media, pop culture, government elites, academia, Silicon Valley — perceiving Christianity as “absurd, meant for the weak and unintelligent.”

He is a former leader of the international and intellectually rigorous order named for St. Augustine, the fourth-century bishop and writer whose vision of the centrality of faith redefined the church and Western culture by helping bury, and tar, the once influential Greek philosophy of Epicureanism. That worldview, which had a following in some elite ancient Roman circles, prioritized happiness through a moderate pursuit of pleasure and avoidance of pain.

The new pope seemed to echo Augustine when he lamented those “settings where other securities are preferred, like technology, money, success, power or pleasure.”

By talking about all of this in his first homily, the new pope signaled that he would make spreading the Gospel into this enemy territory a priority of his pontificate, in strong continuity with Francis.

One part of the homily sounded like a mission statement: “These are contexts where it is not easy to preach the Gospel and bear witness to its truth, where believers are mocked, opposed, despised or at best tolerated and pitied. Yet precisely for this reason, they are the places where our missionary outreach is desperately needed. A lack of faith is often tragically accompanied by the loss of meaning in life, the neglect of mercy, appalling violations of human dignity, the crisis of the family and so many other wounds that afflict our society.”

He added, pointedly, that nominal believers occupy these settings too, people who treat Jesus as a superhero rather than someone who led by his actions, and whose actions true believers need to imitate. He said these Christians live as de facto atheists.

The Chicago-born pope went to Peru as a missionary, and his missionary ethos so impressed Francis, who empowered him and put him in a position to become pope. He ended by telling the cardinals that he, like Francis, saw himself as a simple missionary with the job of spreading the Gospel through his actions. Francis made a habit of excoriating cardinals for putting themselves above their flocks, for living big and forgetting what they were there for. Leo also reminded the cardinals arrayed in front of him, in less harsh but no less uncertain terms, that their job was to be simple missionaries, too.

To emphasize this, the pope spoke of an ancient saint who welcomed his coming martyrdom — being devoured by wild beasts in a Roman arena — because it would remove his body from the picture and let his missionary faith shine through.

“His words apply more generally to an indispensable commitment for all those in the church who exercise a ministry of authority,” Leo said. He argued that the cardinals’ duty was not to take center stage, but to “move aside” and “to make oneself small” so that the faith could grow and spread.

“I say this first of all to myself,” he added.

For about two years, he led the Vatican office that selects and oversees the more than 5,000 Roman Catholic bishops around the world, playing a pivotal role in the church hierarchy. Bishops are the church’s direct and most visible link to the faithful in dioceses around the world, guiding their priests and leading pastoral care. As head of the office, the then-cardinal had an important say in the church’s direction.

Experts said his service in that job — which Pope Francis gave him — was likely to have bolstered his candidacy among the cardinals tasked with selecting Francis’ successor.

“It assured cardinals he has the capacity to take control of the Vatican and continue the attempted reforms launched by Pope Francis,” said John Allen, a veteran Vatican analyst and author of the book “Conclave.”

In the job, Cardinal Prevost met with Francis every Saturday morning to present him a selection of candidates for bishops, said Fernando Arregui, an official with the bishops’ office.

At the same time, Father Arregui said, the job added to his credentials as someone who had a widespread knowledge of the global church.

“He spent two years talking to people from America, Asia, from many continents and many places,” Father Arregui said.

Some cardinals cited Leo’s role in the Curia as a factor in his election. Together with his time in Latin America — he served two decades in Peru and became a naturalized citizen — “the years spent in Rome will all provide valuable preparation,” Cardinal Sean O’Malley, archbishop emeritus of Boston and one of Francis’ top advisers, said in a statement on Thursday night.

Experts said it also helped that Leo appeared to occupy an important middle ground. Unlike Francis, he does not appear hostile to the Vatican apparatus, having been a part of it. Yet, he spent most of his career outside the Curia, where internal rivalries among longtime members can hurt a cardinal’s chances to gather a broad consensus.

“For the Curia he is not one of their kind,” said Alberto Melloni, an Italian historian of the church. At the same time, Mr. Melloni added, he was not seen as “a foreigner who could beat them up.”

“He is a man of the Curia but of another kind,” Mr. Melloni said. “He is part of the tribe but he was not born in the tribe.”

Last August, Leo, then still a cardinal, spoke at St. Jude Parish in Chicago, saying Francis had nominated him for the Vatican position “specifically because he did not want someone from the Roman Curia to take on this role.” The future pope added: “He wanted a missionary; he wanted someone from outside; he wanted someone who would come in with a different perspective.”

More than any single issue, church leaders have been wrestling with a philosophical question: Who deserves a say in determining the church’s future? Before the conclave that elected Leo XIV, The New York Times examined the divisions.