ith a flood of baby boomers getting ready to leave the American work force in the next two decades, prospective retirees are making tough decisions about their futures in an uncertain economy. And companies—especially those in high-tech, science and engineering fields—are scrambling to figure out how to keep high-skilled workers from leaving.

    Executives at corporations such as Northrop Grumman Corp. and Boeing Co. say the brain drain could hurt their bottom lines through recruitment and training costs, and lost productivity. They are encouraging near-indispensable engineers and scientists to opt for "phased retirement."

    Phased retirement typically entails retirees collecting benefits while they continue working for the company from which they retired, usually on a part-time or adjusted basis. Phased retirement arrangements, however, often are negotiated on an ad-hoc basis because many companies are unwilling to establish formal programs for fear that targeting select, high-skilled employees could result in lawsuits.

    "They want to maintain this key talent but have to do it in a way that is not discriminatory," said Lynn Dudley, senior vice president of policy at the American Benefits Council, a Washington-based lobbying group.

    The Pension Protection Act of 2006 eased Internal Revenue Service rules on phased retirement, allowing companies to offer benefits to employees who continue working after age 62, but it left out workers between 55 and 62 who opt for early retirement.

    Without a phased retirement program, "people tend to take their money, retire and go work for a competitor because they weren't quite ready to quit working," Ms. Dudley said.

    The American Benefits Council and the HR Policy Association—a Washington-based group of human resource executives at the nation's largest companies—have argued for lowering the eligibility age for phased retirement for workers between 55 and 62. But companies aren't waiting around for the federal law to change while they lose employees to competitors.

    "My thought is a change in the law [to allow phased retirement for people between 55 and 62] isn't going to take place anytime soon and the brain drain is now," said Dan Yager, senior vice president and general counsel at the HR Policy Association.

    Mr. Yager said that in an effort to help corporations now, a consortium of companies and business organizations is establishing a tool kit to provide strategies for employee retention.

    Ian Ziskin, corporate vice president for chief human resources and administrative officer at Northrop Grumman, Los Angeles, said the consortium of about 35 companies—formed about a year ago—surveyed retired high-tech employees from 11 companies about their reasons for leaving.

    The survey, conducted in March and April, found that about half of the 4,981 respondents would have considered delaying retirement if given the option of working part-time with full retirement benefits or working full-time with partial benefits.

    The survey also showed that employers have a narrow window—about two years before retirement—to offer workers incentives to stay. Plus, 63% said alternatives to retirement would have been more effective if they had known about them within that two-year period.

    Jamie Hale, Dallas-based practice leader for work-force planning at consultant Watson Wyatt Worldwide, said corporations would do well to learn from the survey, rather than focusing on workers' benefits. She said companies have been slow to react to the tide of baby boomers headed for retirement and they "really haven't done their homework" in retaining them. She said companies also should consider innovative ways for retaining retirement-age employees, such as offering bonuses or company stock.

    "My biggest point here in all of this is companies need to be more strategic and think of it in terms of total reward strategy," Ms. Hale said.

    Dianna Peterson, director of strategic work-force planning for Boeing, said the company offers part-time work, telecommuting and job-share options to retain employees. Retiring employees also have the option of retiring, waiting for a brief period and returning on a contract basis through third-party vendors.

    One of those vendors is YourEncore Inc., Indianapolis, which Boeing helped establish in 2003, along with Eli Lilly & Co. and Procter & Gamble Co. YourEncore now works with 40 companies and 4,200 high-skilled contract employees in science and engineering, said Brad Lawson, YourEncore's president and chief executive officer.