"There has always been the assumption that when people leave the work force they want to sever all connections with their jobs," says Robert Zager, vice-president of policy studies at the Scarsdale, N.Y.-based Work in America Institute."But it just isn't so." According to Zager, 50% of all retirees want to keep some contact with work.

Statistics show that the number of workers 65 and over in the labor force is declining overall -- from 3.2 million in 1970 to 3 million in 1980. Yet one out of every five men 65 or over returns to the labor force on a full- or part-time basis for either social or economic reasons, according to Philip Rones, an economist at the Bureau of Labor Statistics in Washington, D.C.

That return is not always easy. Elderly workers often have difficulty finding employment that matches both their skills and needs. The majority of these workers want to work part-time, says Rones, but often the only part-time work available is "a $3.50-an-hour job at the local five-and-dime."

One small company, however, does offer an unusual employment alternative to older workers. ACS America, a New York City-based software development company with sales of $5 million, recently instituted a training center for retirees over the age of 55. ACS's subsidiary, Wave III, located in Bradenton, Fla., trains and then employs senior citizens on its computer programming staff.

"When people think of their grandfathers doing computer programming, they can't quite comprehend it," says John Jacobsen, vice-president of corporate planning at ACS. "But there are vital, capable, brilliant people in that age group who don't want to be retired."

The Wave III program benefits both ACS and the retirees. The elderly get steady employment at a good salary (the average is $90 for the equivalent of a full-time day) and the "flexibility to play golf in the morning and program in the afternoon," says Jocobsen. ACS, meanwhile, can build up its programming staff without having to provide benefits for full-time workers.

ACS isn't the only company employing elderly workers. Aerospace, Lockheed, and Grumman are rehiring their retirees to combat a labor shortage in the engineering and high-technology fields that is expected to reach 17,000 a year by 1990. A professional staff member at the House Select Committee on Aging in Washington says, "They aren't hiring the elderly because it's humanitarian. They're doing it because of real needs."