After one day on the job, Aaron Karo knew investment banking was not for him.

"It wasn't like I couldn't hack it," says Karo, 28, a University of Pennsylvania Wharton School graduate who lives in Los Angeles now. "But I was itching to get out of there."

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Still, he did hang in there for 13 months before quitting to become a writer and stand-up comic.

Such giant leaps are common among the under-30 crowd - even if the career changes cause high anxiety for parents.

"The transition from college to adulthood is insanely difficult," says Penelope Trunk, author of

Brazen Careerist: The New Rules for Success

(Business Plus, May 2007).

"You just spent 20 years learning how to be a student. Then you get out into the real world, and you have to know what to do. It's almost dishonest to say you have everything figured out when you're 22."

The U.S. Department of Labor says twentysomethings switch jobs every 18 months. Of course, that sends some parents reeling - especially if they are footing or have paid the cost of college.

Just one year of tuition at the University of Pennsylvania for 2007 to 2008 was $35,916; at Pennsylvania State University, tuition is $12,844 for state residents. And neither of those figures includes the cost of living space, food or books.

But sometimes early career changes work out for the best.

Karo's mother was worried about seeing her son give up a promising career on Wall Street for a long shot at success in comedy.

"I did know the odds of success in his field were very small," says Helene Karo.

But she trusted him.

"Aaron wasn't the kind of kid who was always coming up with crazy schemes," she said, "and then not following through."

Karo says he went into investment banking in the first place because he admired what his father, Albert Karo, had accomplished as a toy-company executive, first locally and later in New York.

"I always looked up to him, and I still do," Karo says. "I wanted to emulate what he was doing, and studying business was the easiest way to do that."

Karo had done well at Wharton, graduating magna cum laude and giving the college's graduation speech in 2001.

But the itch to write was with him all along.

As a freshman, he started circulating his writing via e-mail (this was before blogs became popular) to 20 friends. Word spread, and more and more students wanted to be on that e-mail list. In time, the e-mails caught the attention of an entertainment manager, who brokered a book deal for Karo - who was working on Wall Street by this time.

Meanwhile, Karo was also dabbling in stand-up comedy.

That first book,

Ruminations on College Life

(Fireside Press, July 2002), has just entered its ninth printing. And Karo, who had also begun dabbling in stand-up comedy, has just completed a 19-city tour through the U.S. and Canada.

He moved to Los Angeles, sold a few comedy pilots, and appeared on CBS's

The Late Late Show With Craig Ferguson

on June 25.

Like Karo, Nicole LaBonde of Havertown wanted to emphasize the lighter side of her life.

LaBonde, 25, graduated with a double major in music and dance from Eastern University in St. Davids in 2005. Immediately after graduation she worked in musical theater and in recreation therapy.

But those jobs didn't pay the rent, and soon LaBonde took on a desk job instead. For the next two years she worked at Tegler McHenry & Associates, a benefits consulting and brokerage firm in Malvern. And for the most part, she liked it.

"I didn't hate my job," she says. "I just needed to get up and move around."

LaBonde had practiced Pilates in high school and college to improve her dance technique, and she decided to explore that option at Equilibrium Pilates, a studio in Old City.

The more she trained, the more LaBonde realized becoming a Pilates instructor would combine her interests of teaching and working with the body.

"I've found this wholeness there that wasn't anywhere else, and I want to be able to share that and make it more available," she says. Six months later, she entered a Pilates teaching program at Equilibrium. Now she's part-time at Tegler, as a consultant, and hopes to start teaching Pilates on a regular basis next month.

Many parents may say they just want their children to be happy, but how many hope their children will quit solid traditional careers?

"My dad worked in a steel mill and my mom worked for a doctor's office. They're normal jobs for the area," says LaBonde, who grew up in Oil City, Pa. "No one is a Pilates instructor there."

Still, her parents were supportive of the career change. And her husband, a music teacher in Upper Darby, said it was worth the temporary financial risk.

Caroline Brobeil's mother wasn't so quick to sign onto the idea of her daughter's switching gears.

"I think I gave her a heart attack," says Brobeil, now 35.

Brobeil graduated from Boston University in 1994 with a degree in public relations, followed by a law degree from Temple in 1997.

"I thought law would be a functional degree," she says. And sure enough she was hired by a small firm right after graduation. But the excitement didn't last.

"I got into my office one day, and I looked over South Philadelphia and thought, 'I can't do this for my whole life. This isn't going to work for me.' "

She'd been on the job only 18 months.

A mentor suggested that she volunteer for a political campaign. So Brobeil walked into the campaign offices of then-Philadelphia City Council President John Street offering to volunteer, and walked out with a job - as deputy press secretary.

"My argument to my mom was, if not now then when? I told her I'm in my mid-20s, don't have a lot of obligations, I don't own any property. Now is the time to take the jump," Brobeil says.

Now that Brobeil has found her career path, her mother is less faint of heart.

"I was happy that she was finding something that pleased her," says Marie Brobeil. "You really have to do what you love to do, so I was happy that she was able to find a way to make it work."

Brobeil is public relations manager for Schnader Harrison Segal & Lewis L.L.P., a Center City law firm, a job she started in August 2005.

"It's a great fit because I get to think about law-type of things and I have that challenge still intellectually, but I am much better suited for public relations," she says.

And she's more confident about giving advice to recent college grads.

"If you're looking to make a big change, planning is key," she says. "Not just for yourself, but for your parents."

"Approach them with a logical, well-reasoned approach," she says. "Explain to them why it's not such a random choice and you have thought it through."

Albert Karo, pleased now that his son is happy and successful, offers this advice to parents:

"If your kid is young enough, I think you have to let them take a shot while they still have the chance."

And if parents are still worried, Jim Marino, director of the Career Center at Rutgers University-Camden, suggests looking at the situation from another perspective: Find examples, he says, of people who did change career paths after college - and turned out well.

Art Garfunkel, for example, has a degree in mathematics. Comic "Weird Al" Yankovic went to college for architecture. And country music superstar Garth Brooks has a degree in advertising.

Contact writer Jen A. Miller at jenmiller27@gmail.com or read her recent work at www.downtheshorewithjen.com.