“We’ve struggled,” said Karen Henderson, principal at St. Rita, which serves kids in prekindergarten through seventh grade. “Parents know they have a lot of choice.”

It’s not only religious private education that has experienced this trend. Secular private—which call themselves independent—schools have seen their numbers drop since the recession, too, the Education Department reports, for many of the same reasons, along with growing interest in homeschooling among higher-income families. “Within the independent school community, there has been this trend of saying, ‘This decline in enrollment is just the Catholic schools,’” said Myra McGovern, vice president of the National Association of Independent Schools. “But it’s not.”

The falloff is forcing private and parochial schools to launch sophisticated marketing crusades—digital billboards along New Orleans’ Pontchartrain Expressway flash the local archdiocese’s slogan “Why Catholic Education?” that’s part of its campaign to enlist students, for example—and other strategies.

Some have elevated their fundraising, using methods as sophisticated as what many private colleges and universities practice. They recruit students from other countries. They offer special programs and events in the summers that bring in revenue. They’re redeveloping buildings and property into profit-making conference centers and hotels.

“Independent schools today cannot be the schools on the hill of yesteryear and expect families to be knocking on their doors and writing checks,” said Nick Stoneman, president of the 157-year-old Shattuck-St. Mary’s School in Faribault, Minnesota, which has added a campus in Beijing with 180 Chinese students, turned its former infirmary into an inn, opened a school store and two cafés, and expanded its golf course from nine to 18 holes and sold off house lots around it.

Thornton Academy, a private high school in Saco, Maine, retrofitted an underused building to house a middle school, then built a dormitory and recruited 155 students from China and other countries, to help maintain enrollment in a state whose supply of school-aged children has plunged. “We can’t just rely on students from Maine anymore,” said Rene Menard, headmaster. “Those numbers are way down.”

Shattuck-St. Mary’s is now considering opening more satellite campuses in China, and in Indonesia, Thailand, Singapore, and Vietnam, and one in Chicago on property the rest of which it would develop to produce revenue for scholarships.

“That’s the kind of thinking independent schools need to have now,” said Stoneman, a former Wall Street bond trader and investment banker. “There’s going to be a have-and-have-not situation … The heavily endowed schools are going to have to tighten their belts, but ultimately will be okay. It’s the other 85 percent that are going to struggle.”