“Internships really are a great way to test new water and gain new skills,” said Ms. Levit, who is also president of Inspiration at Work, a career consulting firm in Chicago. “The benefit comes from immersion; doing is the best way to learn.”

Learning was exactly the objective for Lisa Tresmontan when she agreed earlier this year to take a low-paying internship with Joshua Charles Catering in San Mateo, Calif. In this position, she works nights and weekends helping Josh Feinbloom, the company’s chief executive, with everything from food preparation to event planning. Earlier this fall, Ms. Tresmontan oversaw every aspect of a customer’s wedding reception.

While the moonlighting gig is a lot of work on top of her full-time job as associate sourcing manager for the Pottery Barn, she said she wasn’t ready to take a leap into the catering business without checking it out first.

“I wanted to make sure I liked it, and I’ve actually liked it more than I thought I would,” said Ms. Tresmontan, 31. “The hope is that someday, when I’m ready, I can leave the corporate world behind me and commit full time to catering.”

The experience of a midcareer internship has already paid dividends for David Rose, a 40-year-old music lover.

Following an extensive career in business development, Mr. Rose was laid off from an employer in the software development industry in 2005 and took a 30-day unpaid internship with Yep Roc Records, a small record label in Haw River, N.C. During this time, he worked on some complex recording contracts and learned what he described as a “boatload of insider knowledge” about the industry as a whole.

Earlier this year, after a stint as the director of business development at a nearby software company, he put this knowledge to good use and started KnowTheMusicBiz.com, a service-oriented Web site for independent musicians.