In an elaborate ceremony filled with symbolism, Pope Benedict XVI installed his first group of cardinals on Friday, promoting 15 prelates, including two Americans, to the elite club that chooses his successor.

The beaming new "princes" of the church processed onto the steps of St. Peter's Basilica to applause from a crowd of thousands in the square below, decked out for the first time in their crimson robes.

Benedict opened the ceremony by reading out each of the new cardinals' names in Latin, drawing applause after he pronounced each one.

Archbishop Sean O'Malley of Boston was among them, along with William Levada, formerly the archbishop of San Francisco and Portland, Ore. Levada took over Benedict's old job as prefect of the Congregation of the Doctrine of the Faith, the Vatican's new chief doctrinal watchdog.

Hong Kong's bishop Joseph Zen, an outspoken critic of China, and Pope John Paul II's longtime private secretary, Archbishop Stanislaw Dziwisz, were some of the other more familiar faces.

Security was tight around the square, with uniformed and plainclothes police ringing the area.

Levada delivered introductory remarks to the pope on behalf of all the new cardinals, saying they gave Benedict their unconditional loyalty, "free of concern for ourselves and our own lives, as this scarlet (robe) unceasingly reminds and warns us."

During the ceremony, Benedict will give each man his "biretta" or three-cornered hat whose red color symbolizes not only the dignity of the office but the cardinal's willingness to shed blood to promote Christianity. The new cardinals will get their rings during a Mass on Saturday in St. Peter's Square.

Benedict announced Feb. 22 that he was naming the new cardinals, 12 of whom are under age 80 and thus eligible to vote in a conclave. After the consistory, there will be a total of 193 cardinals, 120 of whom can vote.

While electing a pontiff is the primary task of cardinals, they are also called on to advise the pope on running the Catholic Church.

On the eve of the consistory, Benedict summoned the entire College of Cardinals, including its newest members, for a daylong retreat and asked them to give him advice on pressing issues such as relations with Islam and reconciling with an ultraconservative group whose bishops were excommunicated two decades ago.

Cardinal George Pell of Australia said at the end of the day that he hoped the meeting would "become something of a tradition," noting in particular the discussions on relations with Islam.

"I think the general direction was we have to be clearheaded, charitable and know what we're about and obviously support all those moderate forces everywhere throughout the world who are happy to talk and to try to work for the common good," he said.

Cardinal Castrillon Hoyos, meanwhile, said the Vatican was studying the "best formula" for reconciling with the ultraconservative Society of St. Pius X, founded by the late Archbishop Marcel Lefebvre. The cardinal heads the Vatican commission created to try to negotiate with the society.

Lefebvre founded the Switzerland-based Society of St. Pius X in 1969, opposed to many of the liberalizing reforms of the 1962-65 Second Vatican Council, including the use of local languages in the Mass instead of Latin.

The Vatican excommunicated Lefebvre in 1988, after he consecrated four bishops without Rome's consent. The four bishops were excommunicated as well.

Benedict has made clear he wants relations with the group to be normalized, but thorny issues remain. In August, he met with the current head of the society, Bishop Bernard Fellay, who is one of the excommunicated bishops. Both sides said they had agreed to take steps to resolve their differences.

Fellay has said he believes Rome will grant the society a special status within the church, known as an apostolic administration, where the society and local bishops would have "parallel authority" over Lefebvre's followers.

Following Friday's ceremony, Europe will still have the vast majority of cardinals at 100, 60 of whom are of voting age. Latin America is next with 20 voting-age cardinals, followed by North America with 16. Asia has 13, Africa nine and Oceania two.

The new Filipino cardinal, Gaudencio Borbon Rosales, told AP Television News that the decision by Benedict to name three new Asian cardinals showed that Asia was important to the Catholic Church, home to two-thirds of the world's population as well as economic powerhouses.

"I thank God because we are being acknowledged in the whole world," he said. "The Philippines was considered to be the only Catholic country in Asia, but it is not any more. Now smaller countries are too, like Timor and Korea."