Always Home.

When he was 4, Michael Portegies-Zwart asked his mother, Carolyn, the question that all parents dread: "Where do I come from?" But instead of reaching for the anatomy books, she pulled out the atlas. "[I'm] from the United States, your father is from Holland and you were born in Vienna," she explained. The young boy looked at her quizzically. "Yeah, but where am I from?" he pressed. She shrugged, not quite knowing how to respond. Three years later, the family moved to Rome for his father's job with the United Nations. After living there for nine years and attending international schools, Michael, now 19, finally figured out the answer: "I'm from the world," he says.

Portegies-Zwart is part of a burgeoning community of nomadic kids who are growing up globally. Called third-culture kids--or TCKs--these children of diplomats, aid workers, missionaries, military personnel, journalists, academics and business executives are being raised in a culture that lies somewhere between their parents' native one (the first culture) and that of the country where they are based (the second culture). Unlike immigrant children, they have no intention of staying long in the host country; expat families are transferred as often as every two years. And many TCKs live in privileged situations, with subsidized housing and private schooling, creating a distance between them and neighborhood youth. As a result, TCKs tend to integrate well, but never fully penetrate the local culture.

Increasingly, they are finding comfort in numbers. Global changes--an increase in humanitarian-aid programs, the expansion of multinational corporations, larger embassy staffs and ongoing military activity--are steadily increasing the number of expatriate families. American passports issued in foreign countries have nearly doubled in the last decade, from 3.6 million to more than 7 million. The number of British citizens who live abroad has also risen, from 8.6 million to more than 14 million since 1992. A host of new books and Web sites have popped up recently to serve this growing population and their children, beginning in 2000 with David C. Pollock and Ruth E. Van Reken's popular guide "Third Culture Kids: The Experience of Growing Up Among Worlds." A recent book by Germans Hilly van Swol-Ulbrich and Bettina Kaltenhuser called "When Abroad--Do as the Local Children Do" targets 8- to 12- year-olds and covers everything from re-patriation to saying goodbye to old friends. The Web site Expat-Moms.com deals with specific issues like how to tell the kids you're moving again, and ExpatExpert.com talks about integration and socialization as well as culture shock, grieving and being unable to see grandparents.

All the attention is prompting a dramatic shift in how third-culture kids are perceived. Once thought of as oddball nomads or spoiled dilettantes, children of expats are now more widely viewed as savvy and accomplished sophisticates who are comfortable anywhere. They may grow up playing in the Amazonian jungle or commuting to school on Tokyo's crowded subways. In Rome, which hosts two sets of international embassies (to Italy and to the Vatican) and three U.N. organizations, thousands of third-culture kids zip around on mopeds and play soccer in the piazzas alongside the locals. Most TCKs have firsthand knowledge of everything from world geography and cuisine to high culture and international politics. They learn local languages quickly, are precociously comfortable with adults and mix effortlessly with people of all ethnic backgrounds, says Pollock. All in all they possess an adaptability and a broad-mindedness that is valued more than ever in today's borderless world. "They have much more than a textbook understanding of ...