The study projects that Generation Xers will build wealth at the same rate as earlier generations, but "what they don't have is the same kind of Social Security benefits coming their way, and they are a cohort relying almost entirely on 401(k) plans rather than having any money from defined-benefit plans," said Alicia Munnell, co-author of the report and director of the Center for Retirement Research, in a telephone conference. The age at which retirees can receive the maximum monthly Social Security benefit is slowly increasing, with those born in 1960 or later eligible at age 67, up from 65. Plus, Munnell said, Generation Xers will live longer on average, meaning they'll need more money in retirement. The early baby boomers are "in better shape than the other cohorts," Munnell said.

Senior citizens are leaving the labor force sooner than they did 50 years ago, even though they are living longer, healthier lives, according to a landmark analysis of census data released Thursday.

This is one of several surprising findings in the report on aging, which comes as the first baby boomers are nearing retirement age. The oldest baby boomers turn 60 this year, and the new report suggests that many of them already have left the labor force.

The report attributes the declining work rate among older Americans to the growth in private pensions and Social Security and Medicare benefits. As benefits for older Americans grew in the last half of the 20th century, fewer saw the need to work beyond age 65, said Mitra Toossi, an economist at the Bureau of Labor Statistics.

That may change as more companies turn away from guaranteed pensions and Social Security and Medicare face substantial deficits in coming decades.

Within the next four years, nearly a third of all U.S. workers--including tens of thousands of tech pros--will be over the age of 50, leaving a potential gap of business-tech and vertical industry skills, which could also be worsened on the front end by a shortage of young people entering the technology fields.

Nearly two dozen industry associations, ranging from technology to trucking organizations, have bonded together to create a new Alliance for an Experienced Workforce, a collaborative effort aimed at getting employers to develop strategies of keeping aging American workers viable in the workplace.

"The older worker brings a benefit of knowing how things are done at a company and in an industry, and why," says John Venator, president and CEO of the Computing Technology Industry Association, a member of the new Alliance. CompTIA is encouraging employers to offer older IT workers programs, such as skills certification and training opportunities, to help those pros acquire new tech skills that can complement their decades of industry and business experience, boosting their workforce relevance in the years to come.

In addition to skills training for "hot" IT jobs, including those currently in-demand related to RFID, project management, and security, Venator says employers also need to consider other perks that might entice older tech pros to stay in the workforce, including job-sharing, flex-time, and part-time work.

In addition to earning income, they want to use their experience to do the work they enjoy.

Some corporate executives might want to join the Peace Corps, bankers would build yachts, and mechanics would run greenhouses.

"They no longer have to worry about putting two or three children through college," says Kelley Coates-Carter, AARP Maryland spokeswoman. "They can focus on something they always wanted to do. If they're looking to transition into other careers, one of the first things we tell them is to think about their passion."

However, other boomers will not have the luxury of spending their golden years doing their labors of love. Low incomes or a lack of saving early in their careers has left them with few options as they get older.

"There are some baby boomers who will have to work forever because their employers don't have good pensions," says Mr. Frey, the Brookings Institution demographer. "There are a lot of jobs that are being phased out. They're going to be struggling to find jobs."

In another era, the task of caring for elderly parents often fell to the unmarried daughter who never left home and never worked for a living. But now, in a 21st-century twist on the 19th-century spinster, career women like Ms. Geist who have made their mark in the world are returning home to care for parents in old age.

They are embracing a filial role that few could have imagined in their futures and are doing so by choice. In fact, sociologists are beginning to give the phenomenon a name: the Daughter Track, a late-in-life version of the Mommy Track, a career downsizing popular with younger women.

Women, now as always, bear a disproportionate burden for elder care and often leave jobs, either temporarily or permanently, when the double duty becomes overwhelming , according to recent studies of family care-giving, women in the workplace and retirement patterns. Although there is no precise count of how many women have walked away from careers to care for their parents, more of them than ever are financially independent, unmarried or childless, which makes it more feasible than it might be for women with families at home. And never have more parents needed adult children to care for them, what with long life expectancy and disabling conditions like Alzheimer's disease.

"Smart corporations are paying attention" to the challenges that caring for elderly parents presents, said Meryle Mahrer-Kaplan, vice president of advisory services at Catalyst, which has more than 300 corporate members interested in the issues of women in the workplace. "It's so pressing because you can't plan for it, you can't put it off, and it's not a good-news activity. It weighs people down."

Americans' dreams of early retirement, interrupted by the 2000 stock market bust and the 2001 recession, live on. They have been revived in part by the economy's rebound, soaring home values and the ambitions of baby boomers -- although often accompanied nowadays by the realization they'll still need additional income.

A Merrill Lynch survey last year found that 77 percent of more than 3,400 baby boomers polled planned to work in some capacity in their retirement, with second careers in the mix for some, including 13 percent who intended to start their own businesses.

Money worries aside, starting a new career is within reach for most people, said Steve Vernon, author of the retirement book "Live Long and Prosper."

"The barriers are more psychological than financial," said Vernon, a consultant of Watson Wyatt Worldwide. "People get used to a certain level of (guaranteed) income. Also, a lot of people can't seem to find the motivation to make a change."