ROME -- Pope Benedict XVI took the first major step of his papacy yesterday by reappointing John Paul II's entire Vatican administration, a group of conservative church officials favoring strong central control of Catholic doctrine and a firm stance on social issues.
The reappointments included Cardinal Angelo Sodano, 77, the Vatican's secretary of state and second-highest official, as well as the heads of departments for Catholic education, clergy, and the Vatican's relations with laypeople.
In retaining the current administration, the new pope held fast to his message that he would follow in the footsteps of the popular John Paul II. But Benedict, who galvanized many Catholic conservatives with a recent homily attacking ''relativism" and ''radical individualism," is expected to move in the next few months to replace at least some of his deputies and put his stamp more clearly on the church.
''A few of [the officials] will hardly have time to take their coat off," said Thomas Groome, a Boston College theologian interviewed by phone yesterday. ''It won't quite be like a Republican takeover of the White House, where everyone is gone and whole new teams are brought in, but there will be big changes nonetheless."
As pope, Benedict wields power far beyond his direct control of the tiny Vatican city-state and its annexes in Rome; as the spiritual head of the world's 1.1 billion Catholics he can exercise vast influence over the lives of believers.
He can also use the apparatus of the Vatican to put pressure on political leaders. In his previous job, as Cardinal Joseph Ratzinger, he weighed in repeatedly on important issues in American politics.
In 2003, as numerous governments, including the state of Massachusetts, were debating whether to legalize same-sex unions, the future pontiff issued a document strongly opposing the idea. Massachusetts Catholic bishops went on to play a leading role in the unsuccessful campaign to stop same-sex marriage in the state.
The same year, as the US presidential campaign was getting underway, he said Catholic politicians should not dissent from church teachings on abortion, homosexuality, and euthanasia. In a 2004 letter, Ratzinger suggested that bishops should tell politicians who support abortion rights that they should not present themselves for Communion. A handful of Catholic bishops said they would deny Communion to US Senator John F. Kerry, the Democratic candidate for president, who is an advocate of abortion rights.
Currently, the only significant Vatican post vacant is the one Ratzinger held until this month: head of the Congregation for the Doctrine of the Faith, the powerful office responsible for policing Catholic orthodoxy.
Ratzinger's appointment to the job in 1981 was a strong signal that John Paul II intended to keep the church within strict theological lines after the changes that flowed from the Second Vatican Council in the 1960s. Under Ratzinger, the doctrinal office had a reputation for quickly and forcefully reining in bishops and priests who strayed too far from what he considered correct theology, either in their liturgy, their public statements, or their appearances at events such as gay rights protests.
Now Vatican watchers will be keeping an eye on who the pope appoints to fill that role, and looking for other signs about how he will conduct his pontificate.
''Certainly, he's not likely to reverse his views," Jon Butler, a historian of religion at Yale University, wrote in an e-mail. ''But now, in a new position with many new demands . . . he may adopt more complex stands that reflect the many swirling streams within Catholicism."
With more than 3,000 bishops and several hundred thousand priests worldwide, the Catholic Church is not a ship that turns quickly. But as absolute leader, the pope enjoys almost unique power to shift policy.
''You recall when President Bill Clinton, almost immediately after his inauguration, signed an executive order regarding government policy on abortion? A pope has even more power than that," the Rev. Richard P. McBrien, a professor of theology at the University of Notre Dame, wrote in an e-mail. ''The new pope can make any changes he wants, at any time. He's not likely to do so too soon, but at age 78 he doesn't have a lot of time."
After yesterday's reappointments, another key test will be the first set of bishops Benedict XVI appoints to run the numerous dioceses currently awaiting leaders. Bishop choices are the pope's most direct tool for guiding local churches or fixing perceived problems in dioceses.
Cardinal Bernard Law, who holds a ceremonial position in Rome but does not lead a Vatican office, was unaffected by yesterday's moves.
The new pope will also shape Catholicism through his writings, the encyclicals and other documents that help him set the broader theological direction of the church. Well-known encyclicals in the past have included Paul VI's ''Humanae Vitae" (''Of Human Life"), which condemned birth control and abortion, and John Paul II's ''Ut Unum Sint" (''That They May Be One"), which established possible openings for reconciliation among Christian faiths.
''He probably won't put out an encyclical quickly, unless he has one ready in the bag," said Groome. ''It'll be a couple of years probably until we have an encyclical from him. Meanwhile, we'll watch his sermons, his speeches, his other statements."
Some saw subtle signals in both his first benediction from St. Peter's balcony and his first address to cardinals. According to John-Peter Pham, a professor at James Madison University in Virginia and author of ''Heirs of the Fisherman," a book on papal succession, Benedict XVI's blessing used a formula not used by a new pope in at least a century.
''He's reasserting a lot of old Catholic doctrine," Pham said in a telephone interview yesterday.
Pham also pointed to the pope's address Wednesday to the cardinals, calling it ''extraordinary, rhetorically and grammatically brilliant," but noting that it was delivered in Latin.
''In a way, I would hope that that was a willful signal" of a return to Catholic tradition, said Pham. ''Not so much because I want one, but I hope it was an intentional move, rather than a sign that he's so out of touch that he'd write a beautiful speech without realizing that his audience couldn't understand it."
In coming weeks and months, another key signal could be sent by the new pope's travels. Within two weeks of his 1978 election, John Paul II took his first trip outside Rome, to a small Polish-run shrine to the Virgin Mary outside the city. A gesture of devotion and patriotism, it also prefigured two of the key religious dimensions of his papacy, a quiet attention to the mystical side of Catholicism and a fierce devotion to Mary as an animating spirit within the church.
Benedict's first trip from the Vatican, announced yesterday, will be a visit on Monday evening to a shrine of St. Paul, seen as a founder of both the Roman and the Orthodox churches.
John Paul II's first trip outside Italy -- to the Dominican Republic, Mexico, and the Bahamas -- was not only a great sentimental success among the world's massive Spanish-speaking Catholic population, but also a political gesture. Local churches at the time were under fire from the Mexican government, and John Paul's mere presence carried a sharp point that would become a hallmark of his papacy.
Benedict XVI's only definite travel plan outside Italy thus far is to visit Germany for World Youth Day in Cologne in August. Though an important symbol of continuity with John Paul II, known for his attention to young believers, it also marks a key test of whether the reserved and scholarly new pope can recreate his predecessor's populist touch.
''A lot of his stuff will be symbolic," said BC's Groome, ''but it will be very influential. Anyone who says it's only symbolic doesn't understand the power of symbol."
Michael Paulson of the Globe staff contributed to this report.