Despite rapid recent growth in the number and percentage of older Americans as a part of the population, and despite a change in the law that allows more workers to stay on their jobs past age 65, the percentage of older people who are continuing to work is declining.

Running counter to expanded opportunities to work and economic pressure to work are pressures on older workers to retire early to help prevent layoffs. And, where older workers might once have been tempted to look for a job after a year or so of leisure, the tightness of the job market may be discouraging them, according to Philip Rhones, an economist with the Bureau of Labor Statistics.

According to BLS, since 1979 the percentage of working women between the ages of 55 and 64 has declined only slightly--from 41.9 percent to 41.6 percent. But the percentage of working men that age has dropped markedly, from 73 percent to an average of 71.2 percent for 1981 to date. In the last two months the rate has declined even further to 70.3 percent, according to BLS. At the start of 1970, 83 percent of the men aged 55 to 64 were in the labor force.

Participation in the work force by women 65 and older has declined from 8.3 percent to 8.1 percent, and participation by men has dropped from 20 percent to 18.5 percent.

The decline is less pronounced for older women because of the counter trend of more women working.

Many people anticipated that inflation, having raised living expenses and devalued pensions, would keep an increasing number of elderly workers on the job. "Although it makes good intuitive sense, the data suggests it is not happening," Rhones said.

"Other factors are more important, including a person's health and looking at work as a 'bad' rather than a 'good.' " Rhones added that in many cases, additional years on the job don't increase pensions much, so workers view spending extra years at work as "throwing away" pension years.

The state of the economy, in fact, helps account for the decline in older workers' participation in the work force. "When employers are faced with laying off people, they may not want to lay off younger, skilled employes," Rhones said. Instead they may "sweeten the pot for early retirement."

Notwithstanding the trends reflected in BLS statistics, there are also indications that, in the long run, the older worker will become more commonplace.

For one thing, there are the sheer numbers. "The 65-plus population of the United States is currently growing at a rate twice that of the general population," according to a 1980 study by the Congressional Joint Economic Committee.

"The entry of fewer workers into the labor force because of lower birth rates and the tendency of many workers to select early retirement may lead to development of new work patterns for older persons," the study predicted. "Into the 21st century, employers are expected to be more motivated to recruit and retain older workers than ever before."

The study noted that the majority of older workers still working now indicate the desire to continue working past normal retirement age.

The challenge in the years to come may be in how to design jobs to make maximum use of older workers.