As organ music filled the 115-year-old Catholic church, the Rev. Joseph Tran Van Khoa faced more than 1,000 worshipers and raised his arms. The overflow crowd began to sing.

Khoa, who once studied in secret to become a priest in this communist country, beamed.

The ability to celebrate Mass in the open demonstrates that the Roman Catholic Church in Vietnam is freer than it was in 1975, when its activities were severely proscribed after the communists took control of the unified country. Seventeen years ago, Khoa recalled, he conducted Mass in a small room in the back of a church with 20 or so people. The police questioned him monthly, he said, to ensure he did not hold services openly.

"Life for the Catholic Church is a lot easier now," said Khoa, 44. "But I know that we have a really long way to go."

Vietnam has Southeast Asia's second-largest Roman Catholic population after the Philippines, with an estimated 5 million to 8 million followers. But the government still requires consultation on the appointment of bishops and the selection of candidates for the priesthood. Catholic primary and secondary schools have not been reopened. Catholic-run health clinics and kindergartens in the north remain few. Though Vietnam exchanges delegations with the Vatican for annual visits, it does not have diplomatic relations with the Holy See.

On the other hand, priests are allowed to travel within the country, and Catholics worship freely in their churches. A 2004 Ordinance on Religion loosened various restrictions on religious groups -- allowing them, for example, to conduct charitable activities.

At a time of transition for Catholics worldwide, church members in Vietnam are hoping the government will continue to ease restrictions and further promote its relationship with the Vatican. The Catholic Church, which is officially recognized, has more freedom than some other religions.

Human rights activists and dissidents criticize the government's treatment of other religious groups -- a banned Buddhist church, "house church" Protestants who meet secretly in private homes, and ethnic minority Christians in the Central Highlands and northwest provinces.

The United States designated Vietnam a "country of particular concern" last year, mostly because of such religious restrictions.

Prime Minister Phan Van Khai, who has heralded a new era of relations during a current visit to the United States, said in an interview in Hanoi last week that Vietnam was tolerant of all religions.

"We have six major religions with about 20 million followers," Khai said. "We also have pursued a policy of national unity, including unity among religions. It is the religions themselves that have made great contributions to national liberation and national reconstruction."

In February, the prime minister issued what is called an instruction, allowing house churches to operate legally if they renounced connections to alleged anti-government groups. The government also issued a decree aimed at ensuring that local officials enforced the 2004 ban on forced renunciations of faith.

U.S. officials welcomed the moves, but said Vietnam must follow through on the new rules before the designation, which could lead to sanctions, is lifted.

Last year, the State Department's religious freedom report estimated there were 45 religious prisoners in Vietnam. Since then, U.S. officials said they have revised the figure to six because many cases have been clarified and some prisoners have been freed. But U.S. officials note that a number of religious figures remain on probation -- including the Rev. Nguyen Van Ly, a recently released Catholic priest -- or under other restrictions, such as de facto house arrest.

At Phuc Ngac church, built of Gothic-styled stone graced by Oriental-style carved arches, women in traditional ao dai -- long silk tunics worn over pants -- lined up Saturday evening to take communion from Khoa, placing their hands together and bowing slightly. Two elderly women in ao dai circulated to take offerings from worshipers seated on mats inside the church and on the steps. As they extended red fishnets on wooden poles, people dropped in folded bills, the equivalent of 10 to 25 cents.

After years of closed seminaries, which began to be reopened in the late 1980s, priests are in short supply, although the Catholic population is increasing. Khoa is in charge of four parishes with 4,300 members, unusual even at a time of a shortage of Catholic priests worldwide. To serve them all, he celebrated Mass on Saturday evening, before dawn on Sunday, again at midmorning, at 3:30 p.m. and at 5:15 p.m. -- five times in 24 hours, moving from church to church on a motorbike.

But there were even fewer priests years ago, recalled Nguyen Van Hoa, 72, who is old enough to have attended a Catholic school before they were closed in the north after Vietnam won independence from France in 1954.

"In the past, I had to walk 15 kilometers to attend a Mass," said Hoa, who wore a lavender ao dai and had just finished taking collection. "Now it takes me five minutes."

The diocese is centered a few miles away from Phuc Ngac in Phat Diem, the center of Catholicism in northern Vietnam and home to a 19th-century cathedral of stone and wood, with a scarlet-and-gold lacquered altar and a pagoda-style, multi-tiered roof. On Sunday, the Rev. Peter Vuong, 48, was leading a group of 45, mostly Catholic parishioners on a tour of the cathedral, about 60 miles south of Hanoi. They had chartered a bus from Ho Chi Minh City in the south, where most of Vietnam's Catholics have lived since 1954.

Vuong said such a trip in the past might have landed him in prison. In 1975, he recalled, he was sent to work for two years on a government collective rice farm.

He said he was optimistic that Vietnam would soften its religious policies further. "If the Vietnamese government doesn't change, then it will not catch up with the world," he said. "Especially now that Vietnam wants to have open relationships with other countries, it must take action on the human rights issues."

Ngo Yen Thi, chairman of the Government Committee for Religious Affairs, said that although all bishop appointments must be approved by the state, the government has not objected to any of the Vatican's last seven nominations. The government is "in the process of looking into" establishing official relations with the Vatican, and a government delegation will go to Rome in late June, he said. The government, he said, has "made a big effort" to expand church autonomy and will continue, for example, to facilitate the building of churches.

That would be good news for Khoa. He has struggled for five years to win permission to enlarge a small chapel next to Phuc Ngac church. "Finally, the other day," he said, "I went to the [provincial] people's committee and said, 'I don't know if anybody in Vietnam has been more patient than I!' "

The committee gave him permission to rebuild, but not expand, he said. He said he might appeal the decision to the central government.

The Catholic religion is "a global trend," he said. "So I have faith that one day the church will be free in Vietnam."

A choir rehearses at the 19th-century cathedral in Phat Diem, the center of Catholicism in northern Vietnam. Priests remain in short supply. Prime Minister Phan Van Khai has taken steps to give religious groups more freedom, but U.S. officials want to see concrete results.