Working while vacationing might seem to defeat the purpose—take those unhappy e-mail addicts who obsessively check in while they're ostensibly checked out. But there is a more diverting, more invigorating, and ultimately far more fulfilling sort of work to be done on volunteer vacations, organized trips on which travelers spend their time off doing good for the world. Right this minute, roving volunteers are teaching children, saving imperiled ecosystems, and literally building bridges to impoverished communities. Such efforts can take a person as far afield as she might care to venture (the Arctic, the Amazon), or as close to home as the school down the block. Here, a guide to four groups that need help in the United States.
In Need of...Good Neighbors Where: Kentucky, Arizona, and Washington
What: Global Citizens Network brings volunteers into some of the most beautiful but economically depressed areas of the country: Appalachia, the Navajo Nation reservation, and the Quileute reservation on Washington's Olympic Peninsula. Visitors take on such tasks as building fences, writing grant proposals, and planting gardens.
Duration: Eight days
Volunteers pay: $800, which covers meals and a sleeping area on the floor of a community center (GlobalCitizens.org)
In Need of...Animal Lovers Where: More than a dozen sites across the country
What: Earthwatch Institute matches would-be research assistants with scientists who are studying animals and their natural habitats. A volunteer might record the behavior of wild horses on the Outer Banks of North Carolina or tag terrapins off the coast of New Jersey.
Duration: Most trips last two to 17 days.
Volunteers pay: $950 to $2,650, including meals and shelter, which varies wildly, from tents to country inns (EarthWatch.org)
In Need of...Outdoorsy Types Where: National parks and other public lands, from Maui to Martha's Vineyard
What: The Sierra Club runs about 90 service trips each year, with participants building trails, repairing meadows, and helping with archaeological surveys.
Duration: One week
Volunteers pay: $350 to $600, which covers meals and accommodations ranging from campsites to rustic lodges (sierraclub.org/outings/national/service.asp)
In Need of...DIY-ers Where: New Orleans
What: Habitat for Humanity is still building hundreds of homes to replace those destroyed by Hurricane Katrina. And with on-the-job training, even those who've never handled tools can help.
Duration: From one day to as long as it takes
Volunteers pay: Nothing, but they must cover their own lodging. Habitat's Camp Hope, a school that's been converted into volunteer housing, has a summer camp vibe complete with bunk beds and curfew. ($20 a night, including meals; Habitat-nola.org)
For more opportunities, see Volunteer: A Traveler's Guide to Making a Difference Around the World (Lonely Planet) or Volunteer Vacations: Short-Term Adventures That Will Benefit You and Others (Chicago Review).