PHILADELPHIA - Enrollment in Roman Catholic schools has been declining nationwide over the past five years, a trend that can be attributed partly to the increasing cost of tuition, according to the head of the National Catholic Educational Association.

The association, which met in Philadelphia recently, said in a new report that national enrollment decreased 2.6 percent from the 2003-04 school year to 2004-05, as 173 schools were closed or consolidated and 37 new schools were opened.

There was some growth in enrollment from 1995 to 2000 before it dropped from 2.6 million students in 2000 to 2.4 million this year, Michael Guerra, the group's president, said Tuesday.

"Sustaining (the schools) has been a struggle, but in the last four or five years it has become a very difficult struggle," Guerra said. "We don't want to lose these folks. We don't want to serve only those who can afford the bill."

Twenty-three Catholic schools are closing in Chicago, and schools are also being shut down in areas such as Boston, Brooklyn and St. Louis, Guerra said. But schools are also being opened in some areas, including Atlanta, Minneapolis and Austin, Texas.

Government assistance, in the form of school vouchers or tax credits, is needed along with corporate and individual aid, to help give more students access to a Catholic education, he said.

A top Vatican official, U.S. Archbishop John Foley, told the conference that not enough Catholics who can afford to donate money to the schools are doing so.

"I have personally observed that as Catholics have become relatively more prosperous, they have become proportionately less generous," Foley said. "We must, must, must find ways to finance an affordable, quality Catholic education for every child."

The average cost of tuition for ninth grade at Catholic schools was $5,870 in 2003-04, a 37-percent increase from five years earlier, according to NCEA figures. In 2003, 27 percent of Catholic high school students got financial aid, up from 22 percent in 1998.

NCEA spokeswoman Barbara Keebler said the group does not believe fallout from the priest-abuse scandal of the past several years played any role in the enrollment decline.

While some schools are being closed, more than one-third of the nation's 7,799 Catholic schools reported having waiting lists, the NCEA said. And some businesses and charitable organizations are trying to help make Catholic education more affordable for low- to moderate-income families.

Gregory Ciminera, executive director of Business Leadership Organized for Catholic Schools, said his group has helped raised $5 million for schools in the Philadelphia region in the past year, with most of the money going to families for tuition subsidies.

"Because other funding is drying up," he said, "businesses are going to have to step up."

Calling the funding situation a "crisis," the leader of another charitable group earlier this month donated $300,000 to help find ways to strengthen inner-city Catholic schools and focus on the issues of school closures and enrollment declines.

"These schools should not become the preserve of the affluent," said Carl Anderson, head of the Knights of Columbus in New Haven, Conn. "It's not just a question of numbers. It's a question of ... people not being able to afford it."