Alison Lohman has never been in a foster home, never been around serious violence, never been involved with a man twice her age and never lived on the streets. She has led, by just about any standards, a privileged life, and she is even more thankful for this after vicariously living the life of someone who has not.

“It’s funny, because when I read (‘White Oleander’) I identified so much with Astrid, even though I hadn’t gone through any of her experiences,” says Lohman. Astrid is a teen-ager attempting to survive a series of foster homes after her mother is jailed for murder in “White Oleander.”

“I didn’t even know anybody like her,” says Lohman, who grew up in Palm Springs and won her first theater award, for playing the title role in “Annie,” at age 11. “But once I was cast in the movie, I began seeing Astrid everywhere. At the mall, on the street, at parties. It was like she had been there all the time and I just hadn’t noticed her.”

The role of Astrid, a sensitive, impressionable girl who tries to become what her foster parents want her to be, was one of the most avidly sought-after parts in Hollywood after producer John Wells (“ER,” “The West Wing”) optioned Janet Fitch’s best-selling novel for the screen. It was even more coveted when Michelle Pfeiffer signed on to play the mother. Almost 400 actresses auditioned for the role, including “Gilmore Girls” star Alexis Bledel.

“Besides the fact that it was such a great story, it was a great challenge for an actor, because basically you’re playing, like, four different people, because the character goes through so many changes,” says Bledel.

Complicating the role further was the fact that, in her struggle to find security and love, Astrid makes some regrettable decisions, including sex with an adult. Susan Sarandon says she wouldn’t allow her teen-age daughter, Eva Amurri, who appears in Sarandon’s new film “The Banger Sisters,” to audition, even though she knew the script was good.

“I’m a parent,” she says, “and one of the responsibilities that comes with that is trying to make sure your kids don’t get involved in things they’re not ready for yet. I just thought it would be a rough thing for any kid to be subjected to.”

Wells and director Peter Kosminsky ultimately came to the same decision, which made the hunt for the right actress one who could age convincingly from 15 to 18 over the course of the film even more difficult. So they were greatly relieved when the 22-year-old Lohman came in to read.

“She had the emotional range and maturity to span the age range from 15 to 18 and show the emotional changes Astrid goes through,” says Kosminsky.

“If she appeared too strong, the audience would just take her survival for granted,” says coproducer Hunt Lowry. “And if she appeared too weak, they’d figure she wouldn’t make it, and that would be depressing to watch. What Alison did was convey inner strength while struggling with the natural doubts and insecurity of a girl her age coping that kind of adversity.”

On the day of her interview, Lohman is just trying to summon the inner strength to face a sold-out audience at the world premiere of her film at the Toronto International Film Festival.

Actress Alison Lohman won the lead in White

“I’m really nervous,” she says, a condition her hand-wringing has already telegraphed. “I’m one of those people who kind of likes to be anonymous. I don’t like attention.”

Then why choose acting?

“There’s two kinds of actors, those who like being celebrities and those who like being private, like Michelle, for example. I want to be like that; I don’t want to be revealing personal stuff, which is why this (interview) makes me so weird. It’s like, how do you talk about why you identified with your characters without talking about yourself and your life? I still haven’t figured that part out, and I’ve been thrown into this. And it scares me.”

This much can be revealed: Lohman started doing musical theater when she was 9, sang on the same stage as Frank Sinatra at a Palm Springs charity benefit and spent one high school summer vacation at the Royal Academy of Dramatic Arts in London. She chose to move to Los Angeles and try out for acting roles instead of attending college.

A supporting part in the thriller “The 13th Floor” and the part of Kevin Costner’s daughter in “Dragonfly” were her biggest roles before “White Oleander.” (For the record, oleander is a shrub whose blooms are beautiful but whose leaves are poisonous.)

“I think this would be a hard part to act for anyone, no matter how old you were,” says Lohman. “Then you get even more intimidated when you realize who you’re going to be working with. I had to read with Michelle to make sure we were compatible, and just that made me a nervous wreck, but it ended up working out fine.

“Then, when I had the role, I realized that Robin (Wright Penn) and Ren(Zellweger) would be playing two of my foster mothers, and I was worried all over again. But everybody was so nice to me. They tried to make me comfortable, to just be my friend. Everybody was doing this movie for the same reason because we had all loved Janet’s book.”