Three years ago, after a long career with FedEx, Anne Manning made a difficult decision: She accepted an early retirement offer when the company was downsizing. 
"It was a bit of an identity crisis for me," says Ms. Manning, who is in her early 60s and divorced. "I wasn't sure what I wanted to do." After a lengthy search, she found another position in public relations at the University of Tennessee Health Science Center in Memphis.

"I needed the structure of a full-time job, the stimulation of working with others, and the reward of being productive," she says. "The income was also welcome."

Manning typifies a growing number of women in their 60s and beyond who are extending their careers past normal retirement age. Twelve percent of women over 65 are in the workforce - the highest on record. For men, the figure approaches 20 percent.

Some, like Manning, retire and then return to work, either full- or part-time. Others simply stay on. Whatever their reasons for working - by choice or necessity - they are charting new territory and changing stereotypes of older workers by proving they are highly committed and skilled employees.

Yet these women face challenges, including age bias. Many had interrupted their careers to raise families. They typically earn less than men and are less likely to have a pension and adequate savings. They often live longer and are more likely to be single or widowed. Living alone, they must rely on their earnings and investments to support themselves in retirement.

"Women at 55 or 60 are less likely to have the kinds of income and advantages that men have," says Marcie Pitt-Catsouphes, co-director of the Center on Aging & Work at Boston College. "That means their choices about retirement would be different."

A new study by Putnam Investments, "The Working Retired," found that one-third of newly retired men and women, with an average age of 61, returned to work after 18 months. Two-thirds chose to work, while one-third had to work.

Sometimes just getting hired poses a challenge, particularly for older workers. Although Manning says she had "a lot of good, literally world-class experience" at FedEx, her job search took nearly a year.

Like two-thirds of older women and three-quarters of older men responding to a survey by the Center on Aging and Work, Manning wanted a position that offered a level of responsibility comparable to her previous job.

Other job-seekers are looking for healthcare benefits.

"They are willing to take whatever job they can to cover those expenses," says Jan Cannon, a career adviser in Boston who counsels women in their 60s and beyond who were recently widowed or divorced. "If they're getting Social Security, it's often not enough to cover their needs," she adds.

Many find work as temps or in retail or administrative positions.

Beyond a paycheck, many also need sociability, especially if they are newly widowed.

"For women, the social connections are so important that they would take any kind of job," Ms. Cannon says. "For men, the prestige of the job is more important."

Cannon says that, too often, older women don't recognize the value of their skills.

Yet older employees' skills and productivity often make them far more cost-effective than many employers think, a new study by AARP finds. It refutes the common business perception that workers over 50 cost more than younger workers.

Although men hold more privileged jobs, older women tend to be more committed - more loyal, and willing to go the extra mile for their employers, according to the Center on Aging and Work.

"They may not enter retirement age with the stability of their male counterparts, but their attitude is terrific, regardless of whether they want to work or have to," says Beth Segers, director of market planning for Putnam Investments.

In Ohio, 13 retired nurses - several in their 70s - work part-time as admissions nurses at Cleveland Metro Health Hospital Systems.

"They say, 'This is the best job I've ever had,' " says Coletta Hazel, coordinator of the Wisdom Works program."They like the flexibility of the hours. They bring comfort to patients and their families. And other nurses say that these older, mature nurses help them be empathetic with patients."

Elsewhere in Cleveland, physician Mary Alyce Kraft has been practicing medicine for 54 years, but retirement is not yet on her mind.

"I've had a very wonderful career," Dr. Kraft says. "I feel like I'm doing something worthwhile."

An octogenarian and mother of seven, Kraft asks her older patients: " 'If you retire, what are you going to do?' "

She says many people don't have avocations, and when they retire, they feel at a loss.

Her advice to women and men alike: "Keep active. Keep your mind active. So many people just want to sit down at night and do nothing. It's not good at all."

Whatever choices retirement-age workers make, nothing substitutes for early financial planning, cautions Cindy Hounsell, president of the Women's Institute for a Secure Retirement in Washington.

"Baby boomers think, 'I'll just keep working,' " she says. "That's nice if it works out. But you have no guarantee of the job or no guarantee of health. The No. 1 mistake I see people make is not figuring out how much they'll need to support themselves."

To make it possible for more older workers to hold jobs, Ms. Pitt-Catsouphes encourages employers to make sure they aren't passing over both men and women in their 50s and 60s who might be interested in new assignments or in changing careers.

"It can make all the difference to older workers for employers to think about ways they can respond to their needs in a flexible manner - something a little different from the 40-hour, five-day schedule," she says. "Sometimes older workers feel the only choice they have is either to work full-time or retire full-time."

Sally Hamburg of Indianapolis works four days a week as project director for a nonprofit group serving families with special needs.

As she approaches 70, she says, "I don't think it has affected my accomplishments. I still enjoy what I'm doing. At the same time, at the point at which I decide not to do this, I will have no lack of things to do."

Sandra Hawk Record, a marketer at Texas Christian University in Fort Worth, has worked continuously for 40 years and saved for retirement.

Now a widow, she says, "I see retirement looming, and it's a scary thought. I never got into joining clubs and women's groups. When I retire, I'll be looking for some kind of job that keeps me occupied for 15 or 20 hours a week and brings in a little money. I tell my colleagues they might find me working in the mail room on campus someday. They think I'm joking, but I'm not."

As Manning reflects on her early retirement and subsequent reentry, she says, "I've told my friends who are a little bit younger, 'You need to have an exit plan. You need a goal when you retire, whether it's volunteering or something that gives a sense of being productive and contributing something.' "

Contemplating her own future, she adds, "I don't think retirement is something I'm going to do anytime soon. I will probably work until I'm 70. I just don't see myself not working."