NEW YORK (AP) – At 24, Kristen Bell looks young even for a 17-year-old, which is the age of the sleuthing title character she plays on UPN’s “Veronica Mars.”

Sometimes it gets old.

“I’m carded for R-rated movies,” she reports. “And I get talked down to a lot. When I try to go rent a car or buy an airplane ticket or other stuff adults do, I get, “Okaaaaaaaaay, honey.’

“I remember when I was 18, getting crayons in a restaurant.”

That may be. But spend more than 30 seconds with Kristen Bell – or just take in one of her performances – and you get the message: She is not to be dismissed. A fine-featured blonde little more than 5 feet tall, she is sure to make a big impression.

She played the president’s college-age problem child kidnapped in the David Mamet thriller “Spartan,” and a chaste-looking grifter who was beaten to death on HBO’s frontier drama “Deadwood.” She was the daughter of a drug addict in the Lifetime movie “Gracie’s Choice” and the daughter in the Los Angeles Opera production of Stephen Sondheim’s “A Little Night Music.”

“The first week I was there,” says Bell, meaning Los Angeles, where she moved two years ago after college and several stage roles in New York, “I booked the season premiere of “The Shield.”‘ On this gritty FX cop drama, she played a gang member’s girlfriend who was raped and tattooed on the face.

But that year, she wasn’t so successful landing a series.

“I tested like eight times and booked nothing,” she says, “and every show I tested for got picked up – like “Skin’ and that Norm Macdonald show. It was very grounding to be that close to so many things and not get them.”

Grounding?

“Well, yeah,” she declares, too tactful to brand them “instant flops” outright. “When I saw them, I learned how you can get excited easily. You need to pick your role really wisely.

“This pilot season, I read “Veronica Mars,”‘ she says, flashing an incandescent smile. “Ten pages in, I knew I would kill to get it.”

That wasn’t necessary. In September, Bell premiered as the star of this hip high-school whodunit (airing 9 p.m. Tuesday).

In the rich seaside community of Neptune, Calif., the series’ sadder-but-wiser heroine has assumed a daunting challenge: To get to the bottom of a squalid crime that cost her father his job as the sheriff, spurred her mother to leave home, and turned Veronica into an outcast, where before she was thick with the In crowd. Her best friend was murdered.

After school, Veronica helps her dad (Enrico Colantoni) at his struggling private investigation agency, while her pixyish but bold style has helped earn the show – along with Bell’s pitch-perfect performance – rave reviews. Though no ratings blockbuster, “Veronica Mars” has now won a full-season order.

“She’s a girl who’s not afraid to speak her mind, but she’s not annoying,” says Bell. “She can be really strong, but without being butch. And since my parents split when I was 2, I love the fact that she’s from a single-parent family.”

But more than anything, Bell bonds with her character through their shared loss of a cherished friend.

“When I was 17, my best friend was killed in an automobile accident,” she explains, calling the tragedy “both the best and worst thing that has ever happened to me. I think I’m a happier person because of it, as weird as that is to say, because, once you learn not to take people for granted, you live a lot happier life.”

Growing up in Detroit, Bell was “an outgoing kid” who went on her first audition at 11. A community theater production, “that is where I met Jenny, my girlfriend who was in the car accident.”

But Bell, struck by an unexpected case of jitters, almost quit before she ever got started.

“My mom took me outside and said, “If you do this and you don’t like it, we’ll never have to do it again. We’ll never even have to speak of it.’ So I went back in and did the audition, and was cast in a dual role: In the first act, I was a tree, and in the second act, a banana.”

Her roles have grown richer since then. Just out of college, she was on Broadway alongside Liam Neeson and Laura Linney in Arthur Miller’s “The Crucible,” and in the madcap off-Broadway musical “Reefer Madness” (due this season in a newly filmed version featuring Bell on Showtime).

Even so, her characters, however diverse, continue to dwell in the adolescent age range.

Which may be apt for a young actress who, while waiting at the airport with her 28-year-old boyfriend, watched a stranger approach him to exclaim, “Your daughter’s beautiful!”

“I like playing teenagers,” Bell insists. But she can’t help looking ahead: “It’ll be nice when I can start playing girls in their 20s – without their parents around.”