The beer is starting to spill in the lobby of La Bouche á L'Oreille — Word of Mouth — a crowded, kitschy sometime nightclub on a lonely block in Brussels. It's Saturday night, there's a DJ in the next room, and conversations are taking place in three languages at once. This is a party for past and present E.U. stagiaires, or interns — well-bred 20-somethings from across the Continent who come to Brussels as much to meet their equally cultured peers as to learn the intricacies of E.U. bureaucracy. Near the bar, Genevra Forwood, 24 years old and a few drinks in, chats in English and French with a gaggle of friends. Forwood's contradictions are typical of her cohort. She has a master's degree but "no idea what I want to do long term." She holds a British passport but has spent most of her life in Belgium, with a stint in Mexico. "When I go to England I feel very weird," she says. "I look around and think, who are these people? But the French are still the French, and the English are still English. Nothing will ever change. In Brussels, people speak three, four, five languages, so you don't think about anyone's nationality." She sighs and sips her drink. "But Brussels is not Europe."

Not yet, at least. Most young Europeans think Brussels — which is to say, the E.U. and its institutions — represents nothing so much as gray-suited bureaucrats and cumbersome regulations. And yet while the political idea of Brussels leaves Europeans cold, the experiment it represents is already a reality for an entire generation. And in that sense, the rest of Europe is starting to resemble Brussels more than it thinks. The polyglot, Continental crowd at the Brussels stagiaire party was hardly unique: on any given evening, a similar scene could unfold in the Prenzlauer Berg in Berlin, or the Canal St.-Martin in Paris, or the Docas district in Lisbon, or the clubs in Vienna's Bermuda Dreieck.

The reason is simple: a generation is on the move. In burgeoning numbers and with astounding ease, young adults in Europe are hurdling national barriers, dumping old routines and abandoning traditional career choices in search of their own, highly personalized, custom-made paths to happiness. And for many, that means leading peripatetic, borderless lives that would have been unimaginable a generation ago. All of this is forming the basis for a common European identity in which national and regional ties co-exist with a new and still evolving ésprit de Europe.

Says Michael Gillespie, 26, the head of international research at Informer Brand Development in London: "In terms of outlook and attitudes toward life, there are a lot of shared values among young Europeans. It has to do with a sense of being tolerant and open, and a willingness to try new things." It's no longer unusual for someone like the French novelist Frédéric Biegbeder, 35, to profess little desire to leave France but also "feel totally European. And that means I don't give a damn about France. I go along with John Lennon: 'Imagine there's no countries.' "

And as Lennon might assure Biegbeder, he's not the only one. A Time poll of 1,225 people between the ages of 21 and 35 in Germany, France, Italy and Britain found that a majority of young adults still identify themselves with their native countries. But close to one-third prefer to call themselves European; in Italy, the number is over 40%. And there are countless others who have tried on so many identities that they simply won't — or can't — choose among them.

Paula Romero, 29, was born in Spain, has an English husband and lives in Brussels, where she is pursuing an arts degree at a Belgian university. "A true European is someone who doesn't feel his or her culture is the only thing in town," she says. "Just one culture is not enough these days." Catherine Rubbens, 34, an environmental consultant in London who left the Netherlands after high school, speaks five European languages and says she feels more European than Dutch. "I notice as I start to adjust somewhere that I speak to myself in the language of that place." Rubbens belongs to a distinct class of young Europeans: mobile, multilingual professionals who live, work and play outside their native countries and who bounce across borders — for business or pleasure. To be sure, the advent of such transplants is far from widespread: in 1999, fewer than 2% of E.U. citizens aged 21 to 35 worked in other E.U. countries. But those who do find their sense of belonging transformed. Swiss-born Alexandre Stucki, 28, a European equities fund manager in London, travels twice a week to various cities in Europe and visits his girlfriend in Paris on the weekends. "I feel very much European," he says. "It's a big word, but I don't understand the future of borders and the definition of a nation."

Of course, you don't have to look far to find groups of Europeans — Austrian neo-Nazis, Serbian warlords, ethnic Albanian guerillas, English football hooligans — who still cling to more restrictive, and virulent, notions of identity and nationhood. But for just as many, such boundaries no longer signify anything. Sascha Pichler, 27, was born in Salzburg, Austria to parents of Austrian, Czech, Russian and Serb descent. She spent her childhood in Malaysia, the U.S., Portugal and Germany. After earning degrees from Oxford and the London School of Economics, she moved to Brussels. She rarely sits still: since January she has been to Paris, London, Nice, Milan and Vienna. "It's so automatic. You forget you're abroad and have to pay in a different currency," she says. "Your identity is constantly in question and you feel disoriented. It's unsettling but enriching at the same time."

Europe has long had its share of cosmopolitan globe-hoppers such as Pichler. But now, even those who don't fit into the go-anywhere jet set can now lay claim to a more expansive world. The ease of travel, the advances in communications technology, the ubiquity of multinational brand names, the interdependence of the global economy — all have served to provide young adults with a set of mutual experiences, attitudes and cultural cues. In a Continent where 83% of young West European adults carry mobile phones, this generation's lingua franca is the text message. Europe's nightclubs have made icons out of DJs who spin in different European cities every week, trailed by a transnational community of fans. "There are stronger communions that cut across national identity," says Eric Tong-Cuong, the founder of the French record company Naive. Events like London's Notting Hill Carnival and the Love Parade, the annual three-day outdoor rave in Berlin, have become massive pan-European parties. "Our generation functions tribally but you can belong to several tribes at the same time."