To play a leukemia patient in the recent film Dragonfly, Alison Lohman cut her waist-length blond hair. "I shaved it bald—and then the whole story line got cut from the movie," says Lohman, 23, who gave her tresses to a charity that creates hairpieces for sick kids. "So now someone is walking around with my hair on!"

Drastic dos—thanks to a few good wigs—figure prominently in Lohman's latest role. As Astrid, the troubled daughter of a murderer in White Oleander, Lohman ages from 15 to 18, sporting cuts from do-it-yourself pixie to long Gothic-black locks.
"There were some bad hair days in there," she says. But her performance alongside veterans Michelle Pfeiffer, Renée Zellweger and Robin Wright Penn is earning enviable reviews. The character "needed a sense of an interior that was very different than the exterior," says director Peter Kosminsky. "We saw 400 people for the role and Alison had it." Plus, "she looked like she could be Michelle Pfeiffer's daughter. Look at those cheekbones."

For those she can thank parents Gary, 52, an architect, and Diane, 50, a bakery owner. The Rancho Mirage, Calif., native "used to do little plays with kids in the neighborhood," says her dad. A frequent costar: brother Robert, now 20. "I wanted a sister so bad," Lohman recalls. "I'd curl his hair and put a little flowered dress on him. He was a good sport." Later she found an outlet acting in local theater and singing at parties (including one bash attended by Frank Sinatra).

After graduating from Palm Desert High School in 1997, Lohman landed parts in the '99 flick The Thirteenth Floor and the TV drama Pasadena before nabbing Oleander. (She next co-stars with Nicolas Cage in 2003's crime tale Matchstick Men.) The romantically unattached actress, who lives in a small apartment in L.A., isn't one for nightlife: "I'm more of a homebody; I'd rather be in bed with my book," she says. "I'm a really shy person. I love acting, but the most challenging part is the attention." Better get used to it—or invest in more wigs.