"Education is not a preparation -- it's a continuing necessity," says Katherine Donovan, chairwoman of American University's Institute for Learning in Retirement (ILR).

The institute, in its fourth year on the AU campus, is part of a nationwide movement by colleges and universities to provide special learning opportunities and enrichment programs to older adults who are retired or about to retire.

At a time when undergraduate enrollment of students under the age of 25 is expected to decrease by nearly 20 percent over the next 10 years, educational options for older adults are expanding, and senior Americans are responding by returning to the classroom in increasing numbers. According to the National Center for Educational Statistics, 2 million older adults, or 5.2 percent of the population 55 and over, are learning new skills and exploring new subjects at colleges and universities, community colleges, senior centers and community centers.

"The graying of the campus is one of the most notable trends in higher education," wrote educator Richard Peterson in his 1979 book, Lifelong Learning in America.

"We now realize there is no right age to attend college," says AU President Richard Berendzen. "Mature students not only want to continue to learn, but their skills and knowledge enrich the educational environment."

What makes AU's ILR program unique is that it is planned and taught by senior citizens. Many of the participants are college graduates, although a degree is not required to enroll for the full- or half-year academic term. "The difference between the ILR and other senior learning programs," says Kenneth Young, director of the institute, "is that a membership organization allows retired persons to feel they are still in control of their lives. It's not what the school can do for them but what they can do for themselves."

Learning experiences for seniors aren't limited to the classroom. ILR members attend Folger Theater performances during the Shakespeare study course, visit local points of interest in Washington tours, and get together for folk dancing in physical fitness classes. A weekly luncheon-lecture series and other special events add to the opportunities for new social contacts.

Study group leaders are retired professionals from the arts, government and law. "I started as a student at the institute -- now I'm a teacher," says Marcus Cohn, a partner in a Washington law firm and former law professor at George Washington University, who leads a seminar on public policy and the mass media. "It gives me a great deal of satisfaction to get students involved. They ask a lot of questions -- they're yearning for intellectual stimulation."

Teaching professionals agree that older adults are more motivated than traditional students. "Older adults are not interested in degrees or grades. They are learning because it is enjoyable and personally satisfying," says Berendzen.

"The need for this type of learning program was evident to keep older retired people actively involved," says Jack Blume, a former Washington lawyer who helped develop the ILR four years ago and now teaches a weekly seminar on the Bill of Rights.

After retiring from his law practice in 1980, Blume was planning his own post-retirement future and learned of Duke University's Institute for Learning in Retirement. He later visited other university retirement learning centers at Harvard, Temple University, the University of Southern California and New York's New School for Social Research, where the concept of peer teaching for retired professionals was developed 25 years ago.

"With each visit, I became more and more inspired to start a similar program in the Washington community," Blume says. "What impressed me most about these programs was the dedication and participation of members in teaching and study."

With an initial enrollment of 80 senior students taking 11 study courses, American University's ILR has expanded to 300 members in 40 study group courses -- ranging from anthology to stock market strategies to Latin American revolutions.

"AU's support of this program is our response to the special needs of older adult students in the community," says Young. ILR members are given student ID cards and have access to the university library, health and fitness center and other campus facilities. "We like the mix of older and younger students on campus," Young says, adding that the institute's day program also makes use of campus classrooms that had formerly only been used for evening programs.

"It's one of the best educational bargains in town," says Virginia St. Peter, a retired government worker and third-year student. "This term I'm taking Chaucer's Canterbury Tales -- and I hated it in college."

The Institute for Learning in Retirement is sponsoring an open house Tuesday, Feb. 18, at 1:30 p.m. in Nebraska Hall on the American University campus. Plans for the spring term, which begins March 3, will be discussed. Cost for one term, $125; a full academic year, $200. (202) 885-3920.