NEW YORK — When Ann Kahn was growing up, her family took the same summer vacation every year — a trip to Yosemite. But things are different for her daughter, Ashley.

At 19, Ashley has already set foot on every continent - including Antarctica. And all but one of her journeys abroad were taken without her parents, on trips with other teenagers. She started when she was just 13, visiting Europe with a youth travel organization called People to People Student Ambassadors.

“It’s definitely changed my life,” said Ashley, who is from Green Valley, Calif., and is now a freshman at Sonoma State University. When she was younger, she thought she’d like to be a nurse someday. But now, “I’m a French major. I’d like to work in an embassy. Living and working abroad is definitely something I would like to do.”

Thousands of teenagers like Ashley are seeing more far-flung corners of the world, and at younger ages, than any previous generation of Americans. High schools now routinely organize student trips that require passports. Middle-schoolers hike the rainforest in Costa Rica instead of attending lakeside summer camps with color wars and marshmallow roasts. And older teenagers use the community service they did in Africa as fodder for college essays.

A recent survey of 75 tour operators that belong to the Student Youth Travel Association - http://www.syta.org - found that the top 10 international destinations for youth travel includes China, Peru, Brazil and Australia - along with the United Kingdom, France, Italy, Spain, Germany and Greece. More than half the survey respondents identified middle school as the biggest segment for growth.

“We still have the traditional tours - an eighth grade trip to Washington or a high school trip to New York,” said SYTA spokeswoman Debbie Gibb. “But we’re seeing growth in places like China that you never would have thought of 10 or 15 years ago. The world is shrinking and the students who take these trips are getting younger.”

Gibb said there are no reliable statistics on how many teens travel abroad compared to the past. But the travel bug is definitely going around. Teenagers today “want that notch on the belt,” she said. “They want to say, ’I’ve been to Ghana.”’

Typically these trips cost thousands of dollars. But the pricetags seem more palatable now that many U.S. sleep-away camps charge $4,000 for three weeks in a bunkhouse. A 32-day trip to Europe offered by Westcoast Connection/360 Student Travel - http://www.westcoastconnection.com - is $9,399. A six-week program in Senegal sponsored by an outfit called Where There Be Dragons - http://www.wheretherebedragons.com/ - runs $7,300. Closer to home, the June 27-Aug. 14 session at Camp Mataponi - http://www.campmataponi.com/ - for girls on Sebago Lake in Maine is $9,300.

Often parents write checks for the trips, but some students raise money - especially with school-sponsored trips where kids work together on community fundraising events. (Teachers who agree to chaperone typically travel free.) Sometimes travel organizations offer scholarships for low-income students; others provide advice on finding sponsors - everything from asking local merchants for donations to sending a form letter to everyone you know with a request for $25.

When schools sponsor trips, they tend to have a major educational component, whether it’s practicing French in Paris or studying evolution in the Galapagos. Summer programs “have more of the fun components - rafting, snorkeling and hiking” in addition to cultural experiences, Gibb said.

Westcoast Connection sends 1,500 teenagers each summer on a variety of tours, from language immersion to adventure and specialty sports like golf or snowboarding. But company spokesman Ira Solomon said “there’s definitely been a trend of more substantial summer programming. With colleges becoming so competitive, kids are trying to build their resumes.”

So Westcoast also offers community service, sending kids to work in day care centers in shantytowns in Costa Rica, building houses with Habitat for Humanity in Hawaii, and doing conservation work in an Alaskan rainforest.

Where There Be Dragons offers unusually intense six-week trips to China, Thailand, Cambodia, Vietnam, India, Guatemala, Peru, Bolivia, Senegal and Morocco, capping total enrollment at fewer than 300 students per summer to keep groups small. The trips include homestays, rugged travel, wilderness exploration, language study and learning about local culture, economy, art and religion.

As part of the Senegal trip, students live in a thatched-hut village for two weeks. “They thresh grain, draw water from the wells, they might do weaving or go out in the fields,” said Chris Yager, founder of Where There Be Dragons. For a service project, one group brought in avocado and mango trees, then worked with villagers to figure out where to plant them, how to protect them from animals, and how to distribute the produce. Students on the Senegal trips also get a goat to care for. At the end of their journey, they give the goat to a village to be slaughtered and eaten.

High school students have been taking summer courses on college campuses for decades. But Summer Discovery Pre-College Programs - http://summerfun.com/ - offers some of those classes for American teenagers abroad, at Cambridge University in England, University Politecnica Valencia in Spain and Instituto Lorenzo de Medici in Florence, Italy - in addition to programs at seven domestic campuses, from UCLA to Georgetown. The programs include language immersion and SAT prep as well as specialized subjects ranging from robotics to cooking.

Sometimes the pure fun of travel makes a bigger impact on kids than the educational aspects. Shana Jordan, 17, is spending spring break this year in Italy with schoolmates from Stuart Country Day School of the Sacred Heart in Princeton. She’ll be visiting Milan, Venice, Florence and Rome. But she expects to write her college essay not on Italian art and culture, but on two summer trips she took with ThrillCoaster Tours - http://www.thrillcoastertours.com - visiting amusement parks.

“It’s being able to do what every kid loves - but parents don’t want to take them to do,” she said. “You come for the coasters, but you love it for the friends who turn out to be like family. There’s a whole world of coasters. But I also learned so much about myself.”

How do you find the right program for your teenager? Some groups have long track records and work with thousands of kids. People to People, founded in 1956, sends over 30,000 students and teachers abroad annually. It is one of SYTA’s four largest member organizations, along with EF, WorldStrides and ACIS.

But many smaller, less well-known organizations offer specialized programming that may be a perfect fit. If you’re trying to judge a program “beyond all the fun things your kid is going to see and do,” Gibb said, check the company’s reputation with the Better Business Bureau; ask about the ratio of adults to students (eight to one is typical for eighth grade, 10 to one for older kids); and find out how the program helps kids get to know each other.

“Some programs specifically say we don’t want five kids from the same neighborhood because we don’t want to start out with cliques,” she said.

In addition, ask how emergencies are handled. What happens when someone needs medical care or an accident happens? And how do you stay in touch with your child? Are there regular opportunities to e-mail or call?

Just don’t expect to hear from your teenager too often. “A lot of them have never been away from home more than two to three days,” said Travis Rogers, choir director at Napa High School in California, who has taken his chorus to Italy, Ireland, New York and Hawaii. “They’ve got to learn how to get along with each other. The sense of community and family that gets built are memories that last a lifetime. You really see kids mature.”

Ashley’s mother Ann Kahn agrees. “It gives the kids a different perspective on life,” she said. “I did not travel like this growing up. And I don’t have a huge desire to travel myself. But I think it’s awesome that we were able to provide that for her.”