Now the campaign for the next pope begins in earnest.

In just a week, Roman Catholic cardinals will begin balloting in the Sistine Chapel (search), bound by a strict vow of secrecy.

As they ponder whom to support over the coming days, personal qualities and track records will be crucial. But many think that certain rules of thumb will narrow the field considerably.

A closer look at how that conventional thinking would play out:

— A cardinal. Though in theory any baptized male Roman Catholic is eligible to become pope, a fellow member of the sacred college will almost certainly be selected. That cuts the field from some 500 million male Catholics to 183 cardinals.

— Not too old. The cardinals don't want to hold another election too soon. It's assumed that cardinals 80 and above, who can't vote and are kept out of the conclave, won't be considered. That reduces the number of candidates to 117. Germany's Joseph Ratzinger (search), who turns 78 on Saturday, is at the upper limit of prospects.

In all, 17 of the electors are over 77.

— Not too ill. John Paul I wasn't obviously infirm but because he lived only 33 days after his 1978 election, robust health is deemed essential. The cardinals will certainly bypass their most prominent Asian colleague, the ailing Jaime Sin (search) of the Philippines. Neither Sin nor Cardinal Alfonso Antonio Suarez Rivera of Mexico, who also is ill, will attend the conclave.

— Not too young. On the other hand, following history's third-longest pontificate under John Paul II, the cardinals might well shun someone who would have another long tenure. This could work against, say, the 16 members of the college under age 65, though they include several prominent prospects. Many felt the second-longest reign under Pius IX (1846-1878) was unfortunate.

— Fluency in Italian is a must. Though John Paul II broke Italy's centuries-long monopoly, candidates among the 20 Italian electors may enjoy an early edge. But whether or not a pope is Italian, he's the bishop of Rome and must be a credible leader for that flock. Moreover, Italian is the everyday language used in the Vatican bureaucracy. Command of other languages is an obvious plus in this international office.

— No Poles need apply. Even if there were an outstanding candidate among Poland's three cardinals, which there isn't, the conclave would not hand that nation the papacy twice in a row. It's possible that John Paul's roots will even work against other, non-Polish Eastern Europeans.

— Ditto for Americans. The 11 voting U.S. cardinals can be eliminated because their nation is the world's lone superpower. Catholic memories are long and it was disastrous when French popes who appeared to be operating under French influence moved the papacy from Rome to Avignon (1308-1378). Italians call this the church's "Babylonian Captivity."

— Pastoral experience. Pius XII (1939-58) spent his career as a Vatican diplomat and bureaucrat but all the popes since then have spent time running local dioceses. If this criterion holds, it rules out seven of the Italians.

— Roman experience. On the other hand, it's thought a successful pope must have a grasp of the Vatican subculture. True, neither John Paul I nor John Paul II ever worked at the Vatican but both did academic study in Rome and attended the Second Vatican Council and other Roman meetings.

— Popes usually are diocesan clergy. However, several prominent 2005 candidates come from men's religious orders. Such a pope would be unusual, but not unthinkable.

— The bottom line. If all rules of thumb applied and the college focused on a finding a candidate who was — a cardinal, neither too old nor too young, in good health, non-American, non-Polish, a diocesan priest and an Italian speaker with pastoral and Roman experience — the field would be cut roughly in half.

But, of course, there are often surprises.

In 1978, few imagined the cardinals would actually choose a non-Italian, much less a pope from an Iron Curtain country.