arbara Kinzer, 64, joined Borders Group Inc. in 1992 as a bookseller--her first job in more than 25 years after spending decades unable to work because of her role as a diplomat"s wife.

    "The State Department assured us that my volunteer experience would translate," Kinzer says. "But no would give me the time of day."

    That is until she applied for a retail job at a soon-to-open Borders superstore.

    Kinzer quickly became an assistant manager, then general manager. After five years, she moved from the District of Columbia to Borders headquarters in Ann Arbor, Michigan, to help start a training program. Last year, she transferred to the charitable Borders Group Foundation, where she reviews grant applications.

    "I"ve had this opportunity do this huge number of things after 50 when most of my friends have retired," says Kinzer, whose husband, George, has also joined Borders.

    Borders also is one of the companies recruiting through an online service, Retirementjobs.com, which connects workers ages 50 and older with jobs. Retirementjobs.com is the latest player focused on helping recruiters find qualified mature workers. Rivals include retireejobs.com and Senior Job Bank.

    "The tipping point, we have established, has arrived," says Tim Driver, CEO of Retirementjobs.com. "There is a gap between people expected to exit and enter the workforce that is widening rapidly. It"s the wave of the future: People are redefining retirement and companies have dramatic new needs."

    Because of the aging of baby boomers and fewer young people entering the workforce, some experts predict a labor shortage. By 2014, 21 percent of the workforce will be 55 or older, compared with 16 percent in 2005, according to the Bureau of Labor Statistics. At the same time, statistics indicate that the workplace is becoming less hostile to older workers. Age discrimination complaints to the Equal Employment Opportunity Commission fell for a third consecutive year--down 7 percent, to 16,585--in the year that ended September 30, 2005.

    To appeal to job hunters, Retirementjobs.com boasts that it screens companies and certifies them based on 12 criteria as friendly to age 50-plus workers, Driver says. The site"s database lists 15,000 certified "friendly" jobs. Users can jump into a second tier that lists 60,000 uncertified jobs.

    "Increasingly employers want to be seen as friendly to 50-plus workers," says Driver, a former executive with Salary.com. "They have done their homework and figured out that it makes a ton of sense to be focused on these workers who are twice as likely to stay on the job, a lot more experienced and industrious, flexible regarding their work schedule and pay and, frankly, relate well to customers who frequently these days are older themselves."

    At Borders, for example, 15 percent of the workforce is 50 or older, spokeswoman Anne Roman says. That"s double what it was six years ago, and the nation"s No. 2 bookseller hopes that figure will reach at least 20 percent.

    In addition to job listings, Retirementjobs.com offers sections on continuing education, resources on everything from writing résumés to joining the board of a nonprofit organization, and inspirational stories by older workers who transitioned into new jobs.

    "What we"re creating is a whole environment that"s specialized for 50-plus workers," Driver says. "We"re covering both career topics as well as financial topics that are germane to this group of people who need to have answers to questions like, ‘What steps do I need to take to avoid the wrong impact on my Social Security?"

    Greg O'Neill, director of the National Academy on an Aging Society, says older workers tend to like "transition" jobs.

    "They don"t want to go from full 100 percent work to full 100 percent not work," he says. Though up to half of past generations have said they plan to work past age 65, O'Neill says, only 13 percent have done so.

    "Will the baby boomers be different?" O"Neill asks. "Are they actually going to do what they say: work longer? I think they will."