High school foreign exchange students (search) became so part of American culture in the 1980s and 90s that, for a while, no Hollywood teen movie was complete without one.

But the number of international students at U.S. high schools has dropped significantly in the last decade, partly because schools and families are less willing to play host.

"We don't really have a lot of research into why it is happening, but it is happening. There are fewer students," said John Hishmeh, executive director of an umbrella group for most of the country's big exchange programs.

Some of the decline may be due to visa rules that took effect in the late 1990s that made it more difficult for international students to attend U.S. public schools, he said. Security and political concerns may have played a role too, although the downturn appears to have begun before the Sept. 11 (search) attacks.

Hishmeh said it might be more likely that with the end of the Cold War (search), busy American families and cash-strapped school districts simply became less interested in hosting foreigners.

"We see a lot of schools not wanting to take foreign students because of budget concerns. We see a harder time for programs trying to find host parents," Hishmeh said. "Funding for public diplomacy and interest in public diplomacy really started to drop off in the late 1990s. We need to get back in the game of telling America's story."

Last year, 27,742 foreign exchange students visited the United States through programs accredited by the Council on Standards for International Educational Travel, the organization Hishmeh leads. The numbers were 44,291 in the 1999-2000 school year and 62,005 in 1993-94.

The State Department has noticed a recent downturn in enrollments too, although for a shorter time.

About 39,000 foreign secondary students were admitted to the United States on exchange program visas in the 1999-2000 school year, compared with 28,200 the year of the terrorist attacks and 24,600 in 2002-2003, according to the Bureau of Educational and Cultural Affairs. Unlike the figures from the Council on Standards, those numbers don't include students who come for less than a full semester.

Born in the wake of World War II, high school exchange programs have long helped showcase the American people to nations where the United States was trying to build a better relationship.

Christina Pillot, of State College, is hosting Charttraharn Chareonwong, a 16-year-old from Thailand. She sees her participation in a Rotary International program as a way to help bolster America's image abroad.

"I'm doing my own small part in worldwide detente," she said.

Seven of the 10 places that sent the most students to study in American high schools last year were countries that either fought the United States in a war or were a battleground for U.S. troops: Germany, Japan, South Korea (news - web sites), Vietnam, France, Italy and China. An eighth was Cold War opponent Russia.

The State Department looked to expand on that tradition in 2003 by founding a $10 million program aimed at encouraging student exchanges with Muslim countries.

About 160 students from the Middle East, North Africa and South Asia attended U.S. high schools in the program's first year. This year, enrollment increased to more than 400. Eventually the State Department hopes to expand to 1,000 students.

The challenge may be finding enough American schools and families willing to play host.

Utah passed a law last year slashing money for exchange programs and requiring visiting students to pay tuition to attend public high schools unless they came in a one-for-one swap for an American.

In recent years, some Pennsylvania high schools have hesitated to take exchange students, partly because they feared — incorrectly — that federal education regulations required them to place students with less-than-perfect English in costly special education programs, according to Jim Buckheit, executive director of the state Board of Education.

School officials in New Brighton, Pa., about 25 miles northwest of Pittsburgh, are considering a plan to accept only one or two exchange students stead of their usual four or five. The reason is cost, Superintendent John Osheka said.

"They are wonderful, delightful people to have here," he said, "but we want to make sure our services are not stretched."

Families are less likely to put up an international student these days because they feel pressed for time, said Carolyn Murphy, who was an exchange program coordinator for a decade at North Penn High School in Lansdale, outside Philadelphia.

"I think it's more the American lifestyle, than anything," she said. "I just think American families think they are too busy for exchange students. The families are just so frantic, and so busy doing their own thing that they can't think of anything else."

Program coordinators remain hopeful that a renewed interest will emerge.

American Field Service, one of the oldest and biggest exchange programs, said it saw a 6 percent increase in the number of U.S. families willing to host students last year.

"Our expectation is that it will continue to grow," said Christine Vogel, an AFS vice president. "At this point in the world situation, it is easy to feel powerless. You feel there is nothing you can do. But in actuality, this is something that American families can do."