As many parents struggle to keep their children in private schools, the schools are experiencing their own troubles.

Declining enrollment, coupled with plummeting endowments, has the schools scrambling to maintain their operating budgets and building plans. It is uncharted territory. Private schools traditionally shake off recessions.

Parents, meanwhile, are making sacrifices to avoid uprooting their kids.

Melissa Sheridan and her husband, an engineer, moved from Scottsdale, Ariz., to a smaller home closer to Phoenix Country Day School to cut commuting costs and still send their two daughters to the private school in Paradise Valley, Ariz. Sheridan said she will pick up a part-time job after Jan. 1.

"It's the best choice we ever made," she said.

During the six recessions since 1969, private-school enrollment and giving remained remarkably steady, said Patrick Bassett, president of the National Association of Independent Schools, which represents 1,450 private schools.

This time, some private schools were not prepared and now are scrambling to weather the tough years to come.

Patrick Bassett, president of the National Association of Independent Schools, suggests they be prepared for a 5 percent to 20 percent drop in income.

"There are many variables in play that have never, together, been in play at the same time," Bassett said. Sliding enrollment, more demand for financial aid and shrinking endowments aside, the wealth of families is declining.

For 25 years, private schools raised tuition at a rate that outstripped inflation, and parents continued to pay what now averages $18,500 a year at nonreligious high schools, Bassett said. He worries the cost has reached a breaking point for parents.

To survive, most private schools need to stop hiring, give more financial aid and increase the number of students, Bassett said. For example, if a school faces losing 20 students, it could cut tuition for those students in half and offer the same deal to 20 new students. The net result would be a balanced budget.

Still, private schools need to be careful not to damage the quality of their programs or overload their classrooms, said Geoffrey Campbell, head of Phoenix Country Day School.

Parents want to know "that the school they signed up for ... is the school that remains during the economic downturn," Campbell said.

Mark Schornak said sending his son to Phoenix Country Day is one of his few investments still paying big returns.

"He comes home from school and tells me what they're doing and is so excited about it," said Schornak, a medical illustrator for a Phoenix hospital. "That makes me smile right now, when everything else in going down the tubes."

Some private schools are showing signs of a stressful economy, some are prospering and some don't want to talk about the effects.

In the Phoenix area, at Phoenix Country Day, the costliest and oldest of nonreligious private day schools, enrollment is down 2 percent, to 724 students, and administrators are preparing for as much as a 30 percent increase in financial-aid applications in the next couple of years.

The school's November open house drew 125 potential students, a drop of 30 percent from an open house held at the same time last year.

Religious schools like to say they have a niche product that keeps parents coming back, but even they are not immune. For example, enrollment at Phoenix's St. Mary's High School dropped this year to 788 students, from 800 last year, and it delayed breaking ground for a new building because fundraising for the project came up short.

"People are just scared to commit to larger amounts we've received in the past," said Bridget Costello, the schools' development director.