Lauren Kahn has been trading homes for fun and profit since 1990. But she's not a real estate broker; during vacations, she swaps her McLean, Va. townhouse for homes and apartments in Europe and elsewhere to save on hotels and immerse herself in a foreign culture.

Most years, she says, the best summer exchanges are locked up months in advance. But Sept. 11 made this year different. The terrorist attacks caused potential swappers to hold back, and, even at this late date, she says it's still possible to trade places with a far-off family for a week or two. Long weekends, meanwhile, always seem to be available.

House swapping has been around for years but has gained new impetus lately thanks to the Internet. E-mail has made communication between potential exchangers much faster and cheaper. Web-based exchange services, meanwhile, report growing membership rolls, which shouldn't be surprising. Swappers also say they get a truer sense of a place in somebody's home, away from the usual tourist havens. Many swappers even like the serendipity of listing their homes and entertaining offers from places they hadn't considered visiting. And of course, instead of leaving your own empty house as burglar-bait, you keep the place occupied while you're away.

The ease of exchanges on the Internet
Traditionally based on catalogs, home-exchange services in recent years have moved aggressively onto the Internet, a medium well suited to bringing distant buyers and sellers together. The Net is now home to a bevy of exchange services, several with thousands of listings. In most cases, you join one of these services -- fees tend to range from $30 to $110 a year -- and then work out an exchange with anyone else in the club willing to swap.

Claire Pertalion of Hoboken, N.J., for instance, wanted to rendezvous with some European friends in Paris and so signed up at Digsville.com, one of the Internet-only exchange services (see links at left). None of the Paris offerings were for a suitable time period, but she e-mailed some of the Parisians asking if they could be flexible on scheduling and struck pay dirt with the third one she tried. The result was a charming and trouble-free stay in beautiful Montmartre.

The leading players in home exchange are homelink.org, intervac.org and homeexchange.com. The first two go back to the 1950s as catalog services, but the latter is Internet-only. By lowering barriers to entry, the Net has made the field considerably more competitive. Homelink, which claims more than 12,000 listings, appears to be the largest, even if its Web site is far from the best. The others say their services are set apart by factors such as an easier interface or an eBay-style feedback system, which was recently introduced on Digsville.

Homeexchange.com boasts that its system is open to non-members, significantly widening the exchange pool. The catch is that only members can post their houses. In choosing a service, check to see what proportion of its listings are wherever it is you hope to travel. Homelink boasts that only one-fourth of its members are U.S. residents, and, at least by its own reckoning, appears particularly strong in Europe, Canada and Australia.

That said, any number of these outfits offer ample opportunities for exchange, and the savings are obvious. The real issue is, is it safe to turn over the keys to strangers? "It's the primary question that every first-time exchanger asks," says Roy Prince, who runs homeexchange.com.

The appeal for families with children
But home swappers (and exchange services) report remarkably few problems. Home exchangers tend to be prosperous, mature, well-educated professionals—not the types most likely to trash your place. "You just seem to meet a good class of people" even if you never quite meet face to face, says Ken Hampel, a civil servant in Ottawa, Ontario, whose family exchanged with one in Germany. Things went so well he's now looking into further exchanges.

Home swapping is especially appealing to families with kids, for whom hotel stays and lots of restaurant meals are expensive and often not very enjoyable. The key is to swap with other families that have kids, and therefore kid-friendly homes. Parents who exchange report an added benefit: the kids love playing with all those strange new toys.

Also, when you trade places, you're well aware that the people whose place you're in are at that very moment in your house. And someone bent on theft or fraud can usually find easy pickings closer to home. Finally, users are encouraged to communicate extensively in advance and get a feel for their opposite number. Digsville goes so far as to let people include membership in affinity groups with their listings; owner Helen Bergstein says users love to search on this basis, apparently deriving comfort from dealing with a fellow Rotarian, for instance.

Kahn, an admitted enthusiast -- but also a hardened trial attorney -- says no one has wrecked her house or car or filched anything in the two dozen swaps she's done over the years. The worst thing that ever happened was that some French people left her home a mess, but she and her cleaning lady quickly cleaned it up. In most cases, she says, "I've been at fault more than they have."

If you decide to pursue a home exchange, bear in mind the following:

Walk before you run. You might begin with a long weekend not too far away. If you live in Vermont, for instance, you can probably swap most easily with someone from Boston or New York who wants a rural getaway. Such exchanges are more readily available year-round than that glorious farmhouse in Tuscany you've been dreaming of. To snag such a place, start early -- as much as a year in advance. In other words, it's not unreasonable to start looking now for next summer.

Be flexible. A willingness to accept a variety of locations and exchange times will make it much easier to do a deal.

Don't forget insurance. In this country, your home and auto policies will probably cover your visitor, but always check with your agent or carrier.

Leave instructions. Write up a users manual for your house. Visiting swappers will appreciate it, and you will, too, if it prevents them from doing some unintended harm. Also, if you're friendly with the neighbors, let them know what's going on -- perhaps they can help your visitors in a pinch. If you have a regular handyman, plumber, etc., you might also leave those numbers.

Consider a written agreement. Some Internet exchange services offer these for download, and they're nice for establishing a clear understanding. But you're unlikely to have any kind of legal recourse from 5,000 miles away.

Don't expect the Taj Mahal. People will naturally describe their places in the best possible light, but especially overseas, you shouldn't expect too much. Americans are the best housed people on the planet.

Second homes. Consider swapping your vacation house if you have one. It's probably empty most of the time anyway.

Don't expect the world to come to Cleveland. It may be a great town, but if you want to go to Europe, you'll have better prospects if your home is in New York or California. Washington DC, Miami or Chicago might also work. On the other hand, an American with a kid graduating from Case Western might want to exchange with you in June.

Be sensible. If you have a couple of kids, try to swap with somebody in the same boat. And if you have valuable jewelry or silverware, put it in the safe-deposit box. You can also close off a home office or storeroom, ask that your wine collection be left alone, etc.

Matchmakers, not cops. Remember that the home exchange services are simply bringing people together. They can't guarantee a good experience. They can't even guarantee that your swapping partner will honor his or her commitment when the time comes. Sometimes people do back out, although doing so is considered poor form, especially when plans have been made far in advance.