DISCUSSING her career recently, the actress Reese Witherspoon felt compelled to make a confession. ''I use this threat, whenever I get disappointed with the movie business,'' she said, lowering her voice and narrowing her cornflower-blue eyes ominously. ''I say, 'This is it -- I'm going to med school!' I would love to be a pediatric surgeon.'' Chatting in a TriBeCa restaurant, Ms. Witherspoon veered from such pensive asides to moments in which she spoke giddily, even rhapsodically, about life as a fledgling 22-year-old movie star.
In one breath, she would gush about how exciting it was to work with Paul Newman and Susan Sarandon in the thriller ''Twilight,'' released earlier this year, or to act opposite her boyfriend, Ryan Phillippe, in the forthcoming ''Cruel Intentions,'' an updating of ''Les Liaisons Dangereuses.'' In the next, she would lament the way that the news media glorify her profession. ''I'm so tired of reading about these ridiculous actors and their ridiculous lives,'' she said, sounding convincingly jaded.
The women that Ms. Witherspoon has played on screen, particularly in smaller films like 1995's ''Fear'' and ''Freeway,'' have also been complex, sometimes contradictory creatures; and the four characters she will introduce this fall and winter prove no exception.
In ''Pleasantville,'' a seriocomic fantasy that opens next month, she portrays Jennifer, a hyper-popular 90's teen-ager -- Ms. Witherspoon's kewpie-doll prettiness and pert demeanor still lend themselves to adolescent roles -- who is literally transported to the black-and-white world of a 50's television series. Tracey Flick, her character in ''Election,'' a satire in which she co-stars with Matthew Broderick, could be Jennifer's foil: a rigid, over-achieving high-school student. In ''Cruel Intentions'' and ''Best Laid Plans,'' both due early next year, she portrays, respectively, the trusting but plucky Annette, a younger, modern version of the Madame de Tourvel role played by Michelle Pfeiffer in 1988's ''Dangerous Liaisons,'' and Lissa, a woman who schemes with her lover to escape a desolate town.
''I have to love the character and the director, because I lose myself when I'm making a movie,'' Ms. Witherspoon said. ''When I see the movie, it doesn't even occur to me that it's me I'm watching.''
Those who have worked with Ms. Witherspoon praise her unaffected intensity. ''She commits to a character so completely,'' said Gary Ross, who wrote and directed ''Pleasantville.'' ''And she understands comedy. I think she's going to be an enormous movie star, in the way that Carole Lombard was an enormous movie star.''
The daughter of a doctor and a nursing professor, Ms. Witherspoon grew up in Nashville and at the age of 14 made her first film, ''The Man in the Moon.'' She received glowing notices for her performance as a girl vying with her sister for the attentions of a boy. ''For the first four years I was in this business, I was usually just playing someone's child or girlfriend,'' Ms. Witherspoon said. That changed with ''Freeway,'' in a more three-dimensional role as a troubled, precocious girl with a dark past. ''Once I overcame the hurdle of that movie -- which scared me to death -- I felt like I could try anything,'' she said.
Ms. Witherspoon, who is on leave from undergraduate studies in English literature at Stanford University, still views acting with some ambivalence. ''I don't like a lot of movies,'' she said. ''You have to be selective. I have no desire to be the girl on the cover of six magazines at once. I'd rather wait for the right project to come along. And it always does.''