Natalie Portman is wearing a purple shift tight against her pregnant belly--actually a millet-filled pad. It's a broiling evening in Austin, Texas, on the set of Where the Heart Is, but Portman carries herself with dignity. She takes a seat and with a library book as a prop, is suddenly transformed into Novalee, a knocked-up escapee from a Tennessee trailer park. In this scene, the librarian asks her to find a word in the book's index.

"What?" she says, looking confused, as if 'index' refered to something that should be covered with nail polish.

"I'll start over," the librarian says impatiently. "These are called books. Are you with me?"

Novalee isn't. But Portman, 18, would be. Not only is she a young actress of remarkable power--she acted opposite heavies like Pacino (Heat), Nicholson (Mars Attacks!), Thurman (Beautiful Girls), and Sarandon (next month's Anywhere But Here, previewed on page 122)--but, by all accounts, she's also a whiz kid. At eight, she was attending medical conferences with her infertility-specialist father (and deciding to be a vegetarian). She reportedly scored 1320 on her PSATs at the same time she was writing papers with titles like "A Simple Method to Demonstrate the Enzymatic Production of Hydrogen from Sugar" for science contests. She revised her college-entrance essay 20 times until she was satisfied. And not only did this straight-A student win early acceptance to both Harvard and Yale, she then decided to take six Advanced Placement courses. Isn't senior year when you're supposed to goof off?

But outside the school yard, the girl with the "very neat handwriting" who refuses to cross out in her notebooks (she uses Wite-Out) is by no means a one-dimensional overachiever. The moment the library scene is over, she yanks a pair of gelatinous fake breasts out of her bra and holds them out to me as if she were a four-year-old showing off a particularly creepy crawler. "I'm not waif-thin but I'm small, so they make me wear fake boobs. Otherwise they say I look boyish," she explains, laughing. (And the self-professed non-waif puts her money where her mouth is: Later, when the shoot is over, she doesn't return to her hotel to nibble on nutritious carrots or leafy green salad--she hits the town for toffee mocha chocolate ice cream topped with sprinkles.) Back in her trailer, dressed in a black tank top and a wraparound skirt improvised from her dressing gown (jeans are too hot on this fourteenth straight day of 100-degree-plus weather), she starts chatting enthusiastically about her latest passion. It is Goethe, or maybe Hegel? No, she's telling me about tomorrow's absolute must-see episode of Jerry Springer: people who performed their own sex-change operations. She groans. "Ugh, can you imagine what parts of their bodies they had to cut off?" Clearly, Portman is more fun and interesting than the little goody-goody we've been reading about.

Portman Takes a Pop Quiz

My friends all assume that Portman has rarefied tastes and interests, so I give her a qick pop-culture quiz. She doesn't watch South Park or Ally McBeal, but she keeps up-to-date on Friends (she even remembers he actor who played Phoebe's boyfriend last season--Michael Rapaport) and has seen Airheads (an old Adam Sandler flick). She can name Mariah Carey's last album, but not Limp Bizkit's. She's not a pop-cult junkie, but neither is she a child raised in a Skinner box. And like anyone else in her generation, Portman loves to deconstruct her childhood influences. Consider her casual analysis of The Babysitter's Club:

"When I was a kid, I was a ridiculous reader--a book every day or two. Kids' books, not classics. But I got really upset with The Babysitter's Club. One girl was a tomboy who wore boys' clothes and only liked sports and had lots of brothers. Then there was a girl who was really pretty and an only child, and she loved shopping. But there was no overlap, never a girl who liked reading and theater. No one who liked sports and dressing up pretty. Each character was so clear cut. That made me think all parts of myself--my clothes, my hobbies, the kind of student I was--had to match. I thought if you were smart, you had to wear preppie clothes and your hobbies should be reading and writing. I assumed I didn't know who I was because I couldn't identify with a certain personality type. Then I realized my identity was, I like everything. My favorite movies can be Schindler's List and Dirty Dancing. I can like wearing urban clothes and pretty, flowing dresses. You shouldn't feel like you're going crazy if you don't fit into one category. Maybe my feelings have something to do with the fact that, yes, I'm a total Gemini. I'm not schizo and all over the place, but I have very different sides to myself."

From Wise Child to Typical Teen

Born in Jerusalem to an Israeli father and an American mother, Portman, an only child, spent most of her young life in Long Island. She took ballet classes and hoped to act on Broadway. At the age of 11, she broke into films with The Professional, a movie about a precocious young girl who apprentices herself to a socially awkward hitman in order to avenge the death of her family. "I was lucky the director made me look good when I didn't know what I was doing," she says. Still, this role established what was to become her specialty: playing an adult-like child among child-like adults (think of her Queen Amidala in Star Wars: Episode I--The Phantom Menace). "If I had started out doing movies about kids at camp, you might not have seen me again."

Portman theorizes that people like mini-adult characters because they wish they'd been smart at a young age. What no one realizes, she says, is that those kids have scripts in front of them. But Portman herself borrows from real life: Queen Amidala passes herself off as an ordinary ctizen in The Phantom Menace so she can experience the world without scrutiny; Portman maintains a separate identity, too, using her real last name at home and at school and her grandmother's maiden name, Portman, for work. "Both lives are very rich--I'm not missing half of each one," she says. And how's this for mini-adult behavior: Early in her career, she exerted a measure of control unthinkable for most eager young actors--she refused to play Lolita because she thought the character was sleazy; she withdrew from a starring role in Robert Redford's The Horse Whisperer to appear in The Diary of Anne Frank on Broadway. (Two of her grandparents were Holocaust survivors.) And she agreed to star in Anywhere But Here only after the director toned down the sex scene. In that movie she plays Ann, another wise child, whose flaky, irrational mother smothers her with dreams of the glamorous life.

"Ann is wondering,'How am I going to be as an adult? Am I going to be like my mother? Am I going to be my own person? How can I move on with my life?'" says Portman. Leaving for college is the film's critical issue, and one that Portman faces in her own life. "When I was little, my parents never left me alone with the baby-sitter," she says. "I always went to the movies, to the theater, on vacations with them. But as much as I love my parents, I'm ready to start living on my own." Like scads of her college peers, Portman has a list of parental humiliations she's glad to leave behind upon entering the ivory tower: "I get embarrassed when my parents dance. I'm always telling them,'lower your voice.' After the Star Wars premiere, my dad was so smitten by Natasha Richardson, I was like, 'Dad, stop. You're embarrassing me. Mommy's here. Liam is next to you. And he's like five times your size.'"

At the moment, she sounds as normal as they come. And perhaps the most ordinary thing about Portman is the post-adolescent ambivalence she feels about Where the Heart Is costar Ashley Judd: "Ashley and I played this game called Druthers, where you choose one thing over the other. She said,'Would you rather do one amazing film that goes down in history, and have a really horrible time making it, or would you rather make a lot of pretty good little films and have a great time?' Ashley said she wanted to do one amazing film. I said a lot of little ones. Maybe that's selfish; maybe it's not the artist's answer. But I'd rather be happy."

Three very smart people in my life and what I learned from them.

-My grandfather, who taught me to be quiet when I don't have anything to say.
-James Lapine (director of The Diary Of Anne Frank), who taught me that it's normal to have jealousy and competitiveness in your life and that you don't have to let those feelings upset you.
-Ashley Judd (her costar in Where the Heart Is), who taught me how to pat my itchy face instead of scratching it when I'm wearing makeup, and how to have a good time on a movie set.

Three smart people I wish I knew.

-David Letterman. He seems so smart, but you never get to hang out with him after the show.
-David Hare. His play Via Dolorosa moved me and made me think. After I saw it I wrote him a long letter.
-Jack Hanna (of Animal Adventures). He knows so much about animals. His is the most desirable job.

Three things I'll learn to do in college.

-Laundry
-Wake myself up and make myself go to sleep. I'm a night person, so that's hard.
-Use a computer. I can type a paper. But e-mail, never done it. Internet, never done it.

Three must-haves for my dorm room.

-A constant supply of Jolly Rancher Jolly Jellies.
-Pictures of my friends and family.
-My phone: I'm always on the phone because I'm usually not with the people I want to be with.

Three smart things I try to do when I see a guy I'm interested in.

-Find out about his history and background.
-Initiate a conversation with him.
-Notice how much I think about him--a good way to determine how much I like someone.

What I'm not so smart about.

-I have trouble knowing what I want for myself, as opposed to what I want to do so others will think well of me. For awhile, I wanted to be a doctor. But I figured out that was because my dad does it, and it's a smart thing to do, and I know I can do it well, and if I do it, people will think I'm smart and respect me, and I could help people. But that's not really what I want to do.

Three smart things to eat.

-Ice cream
-Bread
-Chocolate

Finally, three random tips.

-Rub ice cubes on your face to prevent breakouts.
-Shave with conditioner if you don't have shaving cream.
-Use Starbucks mints for every occasion--they're the strongest.