It is cozy here in the Hungarian Pastry Shop, the kind of laid-back place where no one bothers you if you nurse a cappuccino for, say, three hours, so it is popular with students at Columbia University. On the bathroom wall are two inscriptions: "I shit in Bush's mouth" and "Bush's mom is a slut! Barbara, you know it's true." Throughout the place, people are having the kind of earnest and deeply serious conversations that are as integral to college life as a pack of rolling papers.

"I think that's an incredibly paternalistic argument," says a bespectacled girl with an Angela Davis-circa-1972 Afro. At an adjoining table, a goateed guy compares generations. "For our parents, it wasn't a question of whether you were going to work, you just were," he says.

Into this hothouse of ideas walks Julia Stiles.

Today, she does not look like a star whose out-of-nowhere movie Save the Last Dance spent two weeks as the Number One film in the land. No, on this drizzly Sunday she looks decidedly like the Columbia freshman that she is: jeans, red sweater, no makeup, bright blond ponytail, knapsack, the requisite silver thumb ring and a necklace that she got in Costa Rica during a trip with Habitat for Humanity. She has a strong, real-girl body, a palpable vulnerability underneath a hard-shell exterior.

Stiles makes straight for a large mug of coffee. "I get up early on the weekends," she says, "because I usually have schoolwork to do." Stiles' course load is heavy, but she manages to get mostly A's, despite the occasional break from school to do a movie. Recently she spent a week in Prague filming The Bourne Identity, which stars Matt Damon. That screwed up her exams a bit, but how could she say no? Somehow, Julia Stiles is able to balance the disparate worlds of academia and Hollywood, which have little in common, except both are brutally competitive, incredibly draining and insular. (Stiles found out how insular school could be when, on the talk-show circuit, she insulted the cafeteria ladies, which turned into a campus brouhaha.) How, then, does she maintain her equilibrium? "I think about that all the time, I really do," says Stiles, who still found space in her school schedule to host Saturday Night Live on March 17th. "Somehow I just do it. But college will help me as an actress, because it makes me more interesting."

"She's just really in overdrive," says Julia's mother, Judith, a ceramics artist. "It's like a triple type-A personality. Sometimes I worry about that. I said, 'Just lighten your academic load and eliminate a class.' She didn't want to."

"I have to get two philosophy books," says Stiles, swinging into a hushed establishment called Labyrinth Books. "I thought I would avoid philosophy like the plague, but I actually find it really interesting." Accordingly, many of her conversations morph into critical examination. "I went to a Chekhov play with my grandmother, and at the end I was talking about how the first act was so boring. And my grandmother didn't see that at all. I realized it was because I need, like, the constant images changing. I wrote a paper about this. The topic was to name your generation, and the paper was called 'The Channel Changers,' about how my generation grew up on MTV and how much that's influenced our attention span." This is not to say that Stiles is a dry academic: She's just intensely curious about the world around her, interested in a million things at once. In many ways, she is a typical college kid -- rolling into class in pajamas, debating the merits of Britney vs. Christina ("Actually, their music is a guilty pleasure of mine"), watching Survivor, blaring Lil' Kim out of her dorm room, going to dance clubs with a fake ID. She has happily immersed herself in dorm life, with its communal showers and crappy dining-room food and RA meetings. As it happens, one of the people on her floor is her old boyfriend, actor Joseph Gordon-Levitt, who co-stars on 3rd Rock From the Sun and shared billing with Stiles in Ten Things I Hate About You. "We're friends," she says, grabbing a textbook called Paradoxes. "We say hello to each other." Stiles, who says she is unattached these days, looks for "a sense of humor, definitely" in a man. She brightens. "And lately, I have such a thing for Latino guys," she says, breaking into a big grin. "If I'm walking past a guy and I hear something in Spanish, I'm like" -- she whips her head around -- "Wait a minute!"

It is delicately pointed out that on MTV's New Year's Eve show, this particular reporter witnessed Stiles vigorously making out with a tall, handsome Latino guy in between takes with Kurt Loder. "Oh," she says, blushing. "Yeah. We're sort of . . . It's kind of . . ." Complicated? "I don't know," she says. "We're kind of . . . figuring out some stuff." Whatever the case, he is, allegedly, the son of her soccer coach, and he may or may not have to do with Stiles' sudden immersion into Latin culture. "I want to be quasi-Latina or something," she says. "There are girls on my floor who teach me how to salsa and merengue, and I've become fixated on becoming really fluent in Spanish. My New Year's resolution was to watch the Spanish channel every day."

Stiles is extremely confident and, being a born-and-raised New Yorker, savvy and street-smart. Sometimes, however, her New York armor can get in her own way. "I tend to shut myself off from people," she says, leaving Labyrinth Books and heading into a drugstore to pick up razors and conditioner. "It's gotten harder and harder for me to meet new people. It takes a lot of effort to open up to them and spend time with them." Her burgeoning fame has only complicated matters. "If I go out on campus, I'll meet new people, and I'll say hi, but in terms of really having, like, close, you know, intimate friendships with other people, I kind of stick to the same group."

Stiles scans the aisle for hair conditioners. "Which one?" she wonders. She opens up a bottle and takes a cautious sniff. "This one smells pretty good." She grabs another, takes a whiff and squirts a large glob of conditioner up her nose. "I, um . . . I can't believe I did that," she says, blindly grabbing a bandanna from a display. See? She's a real girl, and sometimes real girls squirt conditioner up their noses.

When Stiles has recovered herself, we return to the matter of her putting up walls. "That even reflects itself in relationships, too," she says. "It's like a protective thing. If you say you aren't interested in somebody, then you beat them to the punch." She looks down and smiles a little. "That kind of hurts me when I'm meeting guys. Because I'm like" -- she waves her hand dismissively -- "Yeah, right. I'm not stupid. Whatever."

"Julia was born and raised in New York City, which means that she always had somewhat of a guard up," says her father, John, who is a second-grade teacher in Harlem. "I think it is healthy that she doesn't trust people right away. She has good instincts about people."

And about the movies she chooses. The nineteen-year-old threw herself into Save the Last Dance with zeal. She has taken modern-dance lessons since she was a child, but her character was a ballerina. Unfazed, Stiles took a crash course in ballet and hip-hop and practiced until her toes bled. And she wants you to know that, despite reports to the contrary, she did all of the hip-hop dancing and most of the ballet -- "except a few close-ups of the feet, which were done by a double," she says. Save the Last Dance, which harks back to Eighties movies like Dirty Dancing and Flashdance, is a sweetly appealing tale of a romance between Stiles' character and a black student (Sean Patrick Thomas) in a Chicago school. Who knew that this small film would vault to Number One, making a big pile of Sacajaweas opening weekend ($27.5 million) and knocking Oscar-monger Tom Hanks' Cast Away off the top of the heap? Indeed, much of the movie's success was due to the considerable talent of Stiles, who had already made a splash in 1999's Ten Things I Hate About You. Unlike many of her squeaky-voiced, three-named contemporaries, it is easy to imagine Stiles making a smooth transition into an older, seasoned actress. She has a piercing intelligence that lends a depth and richness to her parts. (You can fake a lot onscreen, but you can't fake intelligence. Witness Denise Richards as a nuclear-weapons expert in The World Is Not Enough. But we digress.) In David Mamet's State and Main, Stiles was utterly believable as a small-town teen waitress -- which seems simple enough, but how many films have you seen in which a lacquered actress awkwardly wields a coffee pot? (Her character charmed Alec Baldwin into bed by wearing real-girl corduroys. "I went to the wardrobe fitting, and I was like, 'Am I supposed to seduce somebody in flannels?'")

Save the Last Dance was groundbreaking in that it was the first teen interracial love story to top the charts. "We were surprised, absolutely," says Van Toffler, president of MTV and MTV Productions. "Unlike the way suburban kids buy rap records, quite often, a white audience won't go see a black movie. But everyone can relate to Julia; she's very real."

Stiles has fond memories of filming the movie in Chicago, where night shoots often turned into rowdy dance parties. "There was one point where we were shooting in the club," says her co-star Kerry Washington, who plays her friend Chenille, "and Julia and I turned to each other at three in the morning, and realized that we were getting paid to dance and have an incredible time in a club in Chicago." She laughs. "You know all the dancing when the credits are running at the end? That was during the last night of shooting at the club, and we just danced for hours -- pulled the producers and the sound guys and the prop guys on the dance floor."

Coincidentally, Stiles' next film is O, based on Shakespeare's Othello, in which she will once again star alongside a man of color, Mekhi Phifer. "People in Hollywood said, 'You don't want to do two of those; you don't want to be typecast,'" says Stiles' mother. "Julia said she liked both stories, and that was the end of it. And she's always wanted to do Othello. When she was a little kid, she went out and got a statue of Shakespeare and put it in her room." Not to put too fine a point on it, but what young girl doesn't have a statue of Shakespeare in her room? And then you think that Stiles has already done three modern versions of Shakespearean classics. Besides playing a teen Desdemona in O and a shrewish Kate in Ten Things I Hate About You -- a spin on The Taming of the Shrew -- Stiles did her own downtown take on Ophelia last year in Michael Almereyda's film of Hamlet, co-starring Ethan Hawke.

The key, in fact, to understanding what forces drive Stiles is in her upbringing, so let us delve into the past of a most unconventional child. When Julia was six years old, she wrote a letter to Edward Koch, then the mayor of New York, proposing a new system of garbage disposal. "I had a ceramics store in Greenwich Village," recalls her mom, "and Julia wanted to work in the store. So she would come with me after school, and sit at the cash register and talk to customers and go through the bills, and when she was idle, she would write letters." Not to Santa, mind you, but the mayor. "Julia saw garbage along the street, and said, 'You've got baskets on each corner, but you should have one in the middle of the block.'" Her mom laughs. "You know, Julia went to a hip school, and it encouraged kids to be politically and socially active."

When young Julia had an issue with her parents, she excelled at arguing her point. "She would write us papers," says her mother. "Things like, at twelve: 'I want to walk home from school alone.' Julia really had a good pitch -- she said, 'I'll walk close to the buildings, I'll be near stores that I know, and if I'm in trouble I can hail a taxi at any time.' She had a solid argument. Eventually we let her walk with her friend Michelle."

"When Julia was nine," says her dad, "she wrote an impassioned letter about why she should be able to stay home alone. She decided not to speak to us but only communicate in writing as she argued her case. It was if she was the prosecutor, and we were on trial. She somehow turned it around that we were bad parents for not trusting her and not believing she could manage it."

Stiles grew up in a Soho loft, the oldest of three kids (her sister, Jane, is eleven; her brother, Johnny, is eight). Being raised by, as she terms it, "loudmouth liberal parents" meant that there were many spirited political discussions around the dinner table. (Don't get her started on the debate that arose when Julia voted for Nader. Johnny was incensed. It got heated.) At a young age, the kids were exposed to a fair amount of culture. "My parents always stressed finding some sort of creative outlet," she says, "so they would take me to dance classes, take me to jazz clubs. There was one called Smokestack's Lightning that we would go to every weekend."

"People there loved Julia," says her mom. "She was there at one in the morning, doing cartwheels and having the best time." The family was supportive and close -- "partly the nature of living in a loft. It's close living, very different from suburbia." Julia's mother made ceramics, her father sold them, and the studio was in the loft, so there were many people passing through, and Julia was exposed to a steady stream of people from different countries.

"The kid never slept," says her mom. "Julia always liked to be doing things." She learned about acting from watching The Honeymooners, performing a different part every night. "One night she was Trixie, one night she was Alice. She was often Ralph. She never took an acting class."

Stiles landed a few commercials, one for Tide, another for Apple Jacks. "I was the bitch who makes fun of somebody for eating Apple Jacks," she says. In her middle school, where white kids where the minority, "Everyone wanted to be a homeboy or homegirl, and I tried to imitate that." Her homey-by-way-of-Soho get-up at that time included door-knocker earrings, a Raiders hat and copious amounts of lip liner, which she would take off before she got home. In her early teens, she went each summer to a "hippie camp" in Massachusetts called Camp Rowe. Those summers were pivotal, helping to seal the confidence that her parents had instilled in her. "It was a bunch of kids who listened to the Grateful Dead and Phish, and you'd have workshops, and they worked a lot on accepting yourself and having self-esteem," she says. On the home front, she switched identities when she went to high school, promptly becoming Grunge Girl. She also began to audition in earnest (she got herself an agent at the age of twelve) and, in 1997, she landed a choice part as Harrison Ford's daughter in The Devil's Own. Three years ago she workshopped a play -- why not? -- that she wrote with a partner at a Sundance writing lab. It was about a girl whose grandfather, like her own, has Alzheimer's disease; and she experiments with psychedelic drugs. Stiles has moved on, however. "I'm just interested in different topics now," she says. The play, like Stiles' grunge phase, has run its course.

Tucked away in a pocket of uppermost Manhattan is the Cloisters, a medieval gem of a museum that Stiles has always wanted to visit. All around this tranquil monument to mid-millennial art, people are clustered in knots, whispering respectfully. Stiles whispers too. "I feel like yelling something," she says. "Screaming 'Fire!' or something." Instead, to rebel, she decides to touch one of the objets d'art labeled do not touch. She looks one way and another, like a cartoon character, then firmly feels an ancient stained-glass window. Stiles stops in front of a wooden tableau of men at a table. "At the beginning of the year, we started reading a lot of Greek literature," she says. "And you think, 'The men really put on their armor and went out to war, and then came home and had huge feasts and got really drunk.'" She stares at the tableau, pondering the thought, her fertile, questing mind a professor's dream. Most of her instructors, by the way, don't know that she is an actress. The few who do are more concerned that she do well on her midterms. Many students, however, know exactly who she is. She estimates that she probably gets recognized once a day. So far, here in the Cloisters, most people are more interested in the carved wooden statue of Martyred Deacon Saint (1325-1350). Whoops, spoke too soon. On cue, here comes White Baseball Cap and his lady friend, Bad Perm. "Can I ask you something! Are you an actress! What's your name?" he says.

"Julia."

"I mean, you were in a movie, like, recently! Traffic?" "No," she says, "but a lot of people confuse me with that actress [Erika Christensen]. I was in Save the Last Dance."

"I haven't seen it," he says. "I actually want to see it, but I just haven't gotten around to it yet!" And so on. Finally he and his friend drift off. It is slightly surreal to see the change in Stiles' persona, from classics-loving student to movie star. She has plenty of teen admirers ("I embrace the teen market," she declares), but she is poised to accrue fans of all ages with a few upcoming releases. There is the aforementioned O, which was her toughest role to date. "It was hard for me, because it was a different kind of character than I'd played before -- very open and trusting. It's easier to play somebody who's cynical." The bloody epic was due out earlier, but "they keep pushing it. The studio's afraid to release it, because they don't want people to associate it with Columbine."

Then there is The Business of Strangers, a dark drama in which Stiles stars alongside the formidable actress Stockard Channing, and which is set for a late-spring release. At present, she is mulling over a few things, but she must structure filming around school. It's tricky, but she can do it.

Stiles' friend Kerry Washington thinks Julia will be an actress to reckon with years down the road. "Her intelligence and commitment and pure talent are going to allow her to have a beautiful career, with profound respect and longevity," she says. "I look forward to working with her when we're both in our sixties." Stiles checks her watch. In a few hours, she will head for the Bronx for a soccer scrimmage. A few weeks ago, she was in Prague filming the Matt Damon movie. And so it goes. Hers is a life of balance and transitions, between Hollywood and school, youth and adulthood. For all her maturity, Stiles still hangs on to her childhood blankie. "When I was little I used to talk to it, like my imaginary friend," she says, stopping to contemplate a profoundly depressing tapestry called The Unicorn Is Killed and Brought to the Castle. "And not that I talk to my blankie anymore, but it's very comforting. If I travel, it's really nice to have it. And it's soft, and it helps me to sleep in hotel rooms." It is getting dark outside. Time for Julia to return to her dorm and her collegiate life, which offers the kind of self-analysis and euphoric highs and hideously embarrassing mistakes that you can only undergo properly at school. And she will finish school, by God. "I know Julia," says her mom. "When she decides to do something, she does it."

"Oh, I'll do it," Julia says breezily, slinging her knapsack over her shoulder -- and who among us would doubt her?