There is no clear front-runner, unlike in some past papal elections, many church experts agree. So the cardinals will be weighing a host of factors, including the candidates' country of origin, age, experience and personality.

Among the most critical questions facing the cardinals is, should the papacy be returned to an Italian, or should the cardinals make the bold gesture of choosing a pope from the third world, where Catholicism is both thriving and threatened by competing faiths?

"A third-world pope would clearly indicate that this is no longer a European church, that we are truly catholic in the sense that the word catholic means universal," said the Rev. Thomas Reese, editor of America, a Jesuit weekly.

To qualify as electors, cardinals must be less than 80 years old. In this election, the cardinals come from more than 60 countries, and more than 60 of them were appointed in the past four years. For many of them, the funeral proceedings and the conclave itself, 15 to 20 days after the pope's death, will offer the first opportunity to take the measure of all the potential candidates firsthand.

"Each one of those cardinals is going to walk into that conclave thinking, 'Which of these candidates is going to go over best back in my diocese, in my country,' " Father Reese said.

With all but three of the cardinal electors having been appointed by John Paul, nearly all his potential successors fit his mold of doctrinal conservatism on issues like abortion and euthanasia, birth control, homosexuality and the ordination of women. So the more pivotal factors are likely to be the candidates' nationality and professional experience.

Vatican observers have spent years now honing their ever-changing lists of cardinals who are "papabile," or potential popes. Although the chosen successor may not have made any of these lists, there are certain names that keep cropping up as the cardinals to watch.

Among the third-world contenders most often mentioned is an African, Cardinal Francis Arinze, a Nigerian with a winning personality, a compelling conversion story and years in the Vatican handling dialogue with leaders of other religions, including Islam - a useful experience for whoever is the next pope.

Several Latin American cardinals are also frequently cited. One is Cardinal Oscar Andrés Rodríguez Maradiaga, the archbishop of Tegucigalpa, Honduras, who advanced a social justice agenda for years as president of the Federation of Latin American Bishops' Conferences. Another is Cardinal Claudio Hummes, the archbishop of São Paulo, Brazil, a Franciscan who was born in Brazil of German parents. He, too, is outspoken about social justice for the poor. But he is also said to be more theologically conservative than his predecessor as archbishop of São Paulo.

But Vatican experts say the Italian cardinals have spent this long papacy figuring out how to get it back, and are not likely to cede it once again to an outsider. The pope, among his other titles, is after all the bishop of Rome, and many believe that if there is a clear front-runner from Italy, he will be considered first.

One Italian being watched is Cardinal Dionigi Tettamanzi of Milan, a moral theologian who is close to Opus Dei, an organization of conservative Catholics. Another is Cardinal Angelo Scola, the patriarch of Venice, a media-savvy intellectual who has written about bioethics, which is surely one of the immediate issues facing the next pope.

Other Italians on the lists of papabile are Cardinal Giovanni Battista Re, who has held several powerful Vatican positions but has little experience in the role of pastor; Cardinal Ennio Antonelli of Florence; and Cardinal Tarcisio Bertone, archbishop of Genoa, a canon lawyer who has served as secretary to the powerful Vatican office known as the Congregation for the Doctrine of the Faith.

Cardinal Joseph Ratzinger, who as head of that office served as the Vatican's enforcer of doctrine, is a favorite of some conservative commentators. The former archbishop of Munich, Cardinal Ratzinger is now among the most powerful bureaucrats in the Vatican and is dean of the College of Cardinals. But he has also been a polarizing figure, and will likely have passionate opponents among the cardinal electors.

It used to take a two-thirds vote to elect a pope. But under rules instituted by John Paul, if the process becomes stalemated, a simple majority of the cardinals could vote to waive the rule and permit a simple majority to choose the new pope. Under this system, a candidate who is unpopular with nearly half the cardinal electors could still become pope.

John Paul was a largely unknown cardinal from Poland when he was elected 26 years ago, and he proved that a non-Italian could give the church an epic papacy.

More than ever, the church is a global, multicultural institution. During John Paul's tenure, the church grew substantially in Africa, Asia and Latin America while shrinking in Western Europe. About two-thirds of the world's Roman Catholics now live in the developing world.

John Paul reduced the power of the Italian cardinals, replacing many with Eastern Europeans. The changes solidified a gradual loss in the Italians' dominance. When John Paul was elected in 1978, the Italian contingent made up about a quarter of the College of Cardinals, already a sharp reduction from 1939, when Italians made up about half the college.

In this conclave, the Italian cardinals will be slightly outnumbered by the cardinals from Latin America. Looking at large blocs, about half the cardinal electors are from Europe, while about a third are from developing countries, though cardinals would not necessarily support a candidate from their own continent.

"Some people say there's going to be an Italian restoration, and there are some candidates, but I don't see that happening," said David Gibson, an American journalist who has worked in the Vatican and wrote "The Coming Catholic Church."

"This College of Cardinals is so diverse, from so many different places, and they have no love for the Italians," Mr. Gibson said. "The Italians put a lot more stake in the Italian claim to the papacy than everyone else does."

It is highly unlikely that the conclave will choose an American. Given the United States' powerful military and economic presence in the world, the College of Cardinals will probably avoid giving it the papacy as well. In addition, many cardinals regard the sexual abuse scandal as an American problem, even though clergy abuse scandals have erupted in other countries, including Australia, Austria, Ireland and the Philippines. But even influential American cardinals acknowledge their slim chances of becoming pope.

"An office like the papacy needs to be free," Cardinal Francis George, the archbishop of Chicago, said to reporters in Rome in 2003. "And to some extent, even the appearance of being in some sense captured by, as we say now, the world's only superpower, would not be helpful to the mission of the church."

Age, which is often a factor, could be once again.

Given John Paul's lengthy pontificate, the cardinals may be inclined to choose a slightly older pope, in his mid- to late 70's, in order to avoid another long reign. Cardinal Angelo Scola of Venice, 63, and Cardinal Christoph Schönborn of Austria, 60, both considered rising stars, are said by many church experts to be too young.

But just as many Vatican observers say that given the long infirmity of John Paul, they will look for a youthful candidate, one who can reinvigorate the office, ruling out someone like Cardinal Jean-Marie Lustiger of France, who is 78.

Perhaps the most important and most intangible question the cardinals in the Sistine Chapel will ask themselves is, "What qualities does the church now need in its next pope?" John Paul was a charismatic, globe-trotting pastor, but he paid little attention to tending the church bureaucracy. As evidence, some church experts point to the Vatican banking scandal and the failure to remove or discipline sexually abusive clergy members.

Some cardinals may want to look to an experience church administrator from inside the Curia, like Cardinal Bertone, Cardinal Re or Cardinal Darío Castrillón Hoyos, who, as a Colombian, would also have the advantage of embodying the church's shift to the developing world.

But George Weigel, a papal biographer and a senior fellow at the Ethics and Public Policy Center in Washington, said that after John Paul's papacy, the cardinals who choose his successor would be unlikely to favor a stay-in-Rome bureaucrat.

"The next pope will not be able to return to the model of C.E.O. of the Roman Curia," he said. "The simple reason is that the world and the church now expect something more of the pope, and the electors know that."