Retired. And ready to work.

After more than three decades as an information-systems manager, Ronald Thomson decided it was high time to retire.

March 1997 marked his gold-watch moment.

But after seven months of doing "grandpa stuff" and delving into his hobbies building cabinetry and model ships, life was getting a little dull.

So when the Tulsa, Okla., resident spotted a newspaper ad for a local job fair, he decided to check it out.

"I talked to several companies ... and they didn't seem to care how old you were," Mr. Thomson says. "The main thing is they wanted experience."

The result was a one-year assignment with IBM on a Y2K project.

In the not-so-distant past, older workers were considered over the hill - technological dinosaurs - the first fired and the last hired. But times are changing, albeit slowly. The word "senior" now often signals "experience."

And more and more firms are working harder to attract and retain older professionals - many of them reactivated retirees like Thomson. "We're looking to recruit additional senior workers," says Lynn Taylor, director of research at staffing firm Robert Half International based in Menlo Park, Calif. "They have a vast amount of experience that is invaluable and irreplaceable - and our clients are thrilled to tap that expertise."

Some just want more out of their days than a good golf game. Others have taken early retirement but have no intention of closing up shop yet. They tend to sign on as project-based consultants and contractors.

Still others are jumping in as temporary CEOs or eschewing retirement altogether to mentor young up-and-comers.

No doubt the biggest factor pushing the trend is the tight labor market. With the low 4.2 percent unemployment rate, virtually every company has been forced to broaden its candidate pool. As a result, older professionals, shunned in the past by many companies, are getting a warmer reception.

David Kerstine of Raleigh, N.C., who retired from IBM in June after a 30-year career at the computer giant, has been pleasantly surprised.

When he hit his mid-50s, the former senior marketing manager had no intention of hanging it up. Yet he didn't think he had a chance at landing a job in today's high-tech marketplace, where directors in their 20s dominate.

"I was going to start my own company," Mr. Kerstine says. "I thought I was too old to get another job. But I'm not sure that's true." In fact, he's already had a bite from an Internet start-up - a dream job for him.

Indeed, small and medium-size companies seem to have been first to shed the age barrier. These businesses are growing fast, and that has forced them to focus on skills and knowledge - rather than age.

Consider Sam Sanders, who landed a job earlier this year as vice president of sales for OpenOrders, a 27-person software company in Newton, Mass.

Mr. Sanders spent nearly 40 years in sales in the computer industry. The company had reviewed more than 100 rsums before it received his. But when it came in over the Internet, it took them only 45 minutes to respond.

Several other factors are slowly pushing companies to consider older workers. Downsizing has not only thinned the ranks but also depleted a depth of knowledge and experience.

"You can teach somebody technical skills any day of the week," says Ms. Taylor of Robert Half International. "But you can't amass [quickly] 20 to 30 years of business savvy and interpersonal skills that only time develops."

As a result, companies are working harder to hang on to the senior workers they do have. In a survey of 586 large employers, consulting firm Watson Wyatt Worldwide found that 16 percent offer phased retirement, while 28 percent say they may set up such programs in the next three years.

Yet "companies aren't moving nearly as quickly as they should be," says Marilyn Moats Kennedy, a career counselor in Wilmette, Ill., whose clients include older workers. "By the time they wake up and say, 'We should be doing something with our about-to-be retirees,' those people will be working for other companies."

Also likely to force companies to face this head-on is a looming worker shortage.

The number of new work-force entrants is expected to shrink significantly. Couple that with the aging of America's 76 million baby boomers - the first of whom will be eligible for retirement in 2001 - and many labor-watchers are predicting a severe talent gap in the next decade.

The next challenge for companies will be to attract and retain senior workers, many of whom aren't heading back for the money alone but because they crave new challenges as well as a chance to contribute - and have fun.

Thomson, for example, wanted to be back in a high-energy environment."I missed the people," he says matter of factly.

Yet he says management was a bit concerned that he had so much experience. "They were afraid I'd come in and want to run the project," Thomson says.

To put them at ease he told them he didn't want to attend any staff meetings or make decisions. "I just wanted to work," he says. "They were tickled to find someone who could do the work [and] who didn't want to take the glory."

And they did tap his talents. "Even though they liked to make all the decisions, they would ... run things by me," he says.

One of the biggest draws for retirees is flexibility - most don't want to work 50-hour weeks.

Robert Phillips of Walnut Creek, Calif., spent nearly 30 years working in finance for large corporations, including a stint as chief financial officer.

He knew he wanted to keep working - but on his terms. So Mr. Phillips has spent the last 15 years as an independent consultant for small companies. He works six to nine months a year - which leaves time for volunteer projects, such as helping his church upgrade its accounting system.

"Only once in my life have I thought about retiring. I was sitting on a ski lift," he says. "But I don't need to retire ... I can work when I want to work."

Yet most experts agree companies have been slow to change their attitudes. "I don't think any of this is rapid and massive, but there is a growing appreciation [of older workers]," says Mardi Hack, a managing consultant with outplacement firm Drake Beam Morin in Raleigh, N.C.

And many older workers say age discrimination endures. Sanders of OpenOrders admits that he takes off his hearing aid and glasses for interviews.

And he edits his 39 years of experience down to a page. "It may not be a company policy not to hire people over 60," Sanders says. "But at many companies, the people who screen rsums are looking for excuses to throw them away. Age is one of them."

Adds Phillips: "If I were going to buy a business, I would heavily populate it with mature workers - just because I can see what they can do."

TIPS FOR REENTERING THE JOB MARKET Thinking about rejoining the work force or negotiating a flexible work arrangement? There's never been a better time. Here are some dos and don'ts for older job hunters:

*Keep your rsum to one page - even if you've been working for 30 years.

*Include only relevant experience. No need to document to college days.

*Don't put down that you've worked at a company 22 years - use dates. Let the interviewer do the math.

*Don't mention that you took early retirement or that you are thinking of retiring in a few years.

*Show your energy and enthusiasm.

*Don't apologize or act defensive about your age.

*Emphasize that age has nothing to do with learning new concepts.

*Embrace technology. If you don't have at least a basic understanding of computers, take a class at night.

*Maintain memberships in trade organizations and professional groups and keep your networks current.

(c) Copyright 1999. The Christian Science Publishing Society