Many people find it difficult to change careers because they think they have to do it in one big leap. But you can start by taking small steps that will lead you where you want to be professionally, without losing significant income or disrupting your family.

Here are five ways to make the transition.

1. Build on functional skills. If you like using your core skills and knowledge, consider transferring them to a different industry or field.

Lucinda Wright was a marketing executive for Battle Creek, Mich., cereal maker Kellogg Co. for nine years, rising to vice president of marketing for natural and frozen foods. She then started a consulting business that helped companies with marketing issues. Meanwhile, she volunteered at her graduate business school, the Eli Broad School of Management at Michigan State University. In 2004, when the school needed a new director of career services, Ms. Wright was offered the job.

She now markets the school's M.B.A. program and helps students market themselves to employers. "I'm applying my experience and knowledge to new targets," says Ms. Wright, who is 43.

If this type of career change might work for you, identify your key functional skills and experience and repackage them in a resume aimed at the new field. Next, think of employers to approach and network to learn of possible openings.

2. Return to school. This can help you enter a new field that requires educational credentials that differ from your current background.

After earning an engineering degree, Joe Flerlage joined Underwriters Laboratories Inc. in Northbrook, Ill., and worked his way up the ladder to become an engineering group leader. But he dreamed of becoming a lawyer and decided to attend the DePaul University College of Law at night while continuing in his engineering job during the day.

He commuted to class in downtown Chicago after work and studied at night and weekends and during lunch. After three years in law school, he resigned his engineering job to join a law firm. He finished his last year of law school while working as an associate at his current firm, Brinks, Hofer, Gilson & Lione, a 120-attorney firm in Chicago.

This strategy isn't right for everyone because of the time it requires, says Mr. Flerlage, now 38. However, he says he made more money immediately as a law associate than he did as an engineer with nearly 10 years' experience.

3. Start a parallel career. This is a career that begins while you continue in your former field.

After relocating to New Orleans for her husband's career 1997, attorney June Coldren needed to pass the state's bar exam before she could practice. Meanwhile, she helped her husband set up and run a consulting firm serving oil-and-gas companies.

After she passed the bar, Ms. Coldren did pro bono work to learn more about the law field in Louisiana and explore whether to join a firm or start her own firm. Meanwhile, she helped with the paperwork for her husband's company at night. When her husband accepted a full-time job, he urged her to continue with the consulting business.

Ms. Coldren decided to take his advice and learned the oil-and-gas industry from the ground up. Ten years later, her firm, Cenergy Corp., has logistics services and consulting arms that contract out rig and wellhead supervisors, geophysicists and other exploration-and-drilling professionals.

If you keep your day job, while working weekends or at night in a second profession, be careful not to antagonize your primary employer, since companies don't always view moonlighting favorably.

4. Make an internal move. If you like your current company, consider a change of jobs there that launches your career in a new direction. Identify unfilled needs -- perhaps things others don't want to do -- and volunteer to do them while in your current job. You may be saddled with extra work temporarily, but it may get you into the new area or a promotion.

"Seek new learning opportunities and ways to expand your skills," says Arlene Hirsch, a Chicago career counselor.

5. Go cold turkey. Suppose you don't want to stay in your current job another day longer. For you, quitting outright to enter a new field may be an option, especially if you can survive temporarily without an income.

Deborah Bolin wasn't making enough money as a photo-journalist in Dallas and grew tired of working side jobs to pay the bills. She quit to get her real-estate license and became a mortgage broker to learn the home-sales industry. In three months, she made $60,000, more than she had ever earned in a year, says Ms. Bolin, who is 53. She has since moved to Monroe, La., and is selling real estate full time.