In May 1977, 44 years after being thrown out of Amherst College for getting married, Edgar Clark, of Washington, received a bachelor's degree from Georgetown University.

Clark, 66, is a retired foreign correspondent for United Press, Time Magazine and the old New York Herald Tribune. He said he "just checked in at Georgetown to find out what the hell it was all about" and he stayed around "because I found it very interesting."

Although he was only three credits shy of graduation when he was tossed out of Amherst for violating the rule against marring, Clark had to earn 45 credits to quality for his Georgetown degree. He liked the work so well that he now is working on a PhD in Russian studies.

At 56, Arly Bever, a biochemist retired on disability from the National Science Foundation, has enrolled at George Washington University in a paralegal training program designed specifically for people age 55 and older.

"I wanted to get into some kind of volunteer work that would be useful to someone or some organization," said Bever, who has a PhD, "and I could see the degree in biochemistry wasn't going to help. So I took the course in paralegal training. Most people when they retire don't want to syay home and twiddle their thumbs."

Clark and Bever are only two of 1,627,000 persons age 55 and older who are enrolled in college, according to estimates by the American Association of Retired Persons' Institute of Lifetime Learning.

Roughly a fifth of the 3,300 postsecondary institutions in the United States offer courses designed specifically for older persons, a 20-fold increase since 1970.

Most are two-year community or junior colleges, but private and state-supported colleges are following the lead.

Twenty-eight states, including Maryland and Virginia, as well as the District of Columbia, offer free or reduced tuition to older persons enrolled at public institutions.

"They're a valuable but underutilized resource," says Vicki Gottlich, who directs the paralegal training program for senior citizens at George Washington University. "They may be retiring at 55, but they're not old at 55. They're not old at 65 and some of them aren't old at 75. They're eager and competitive students."

Especially in the Washington area, where there are liberal retirement and pension policies for government employes, the senior citizens' return to campus is a movement whose time has come.

In the last two years, community colleges and state universities in the District, Maryland and Virginia have initiated tuition waiver policies for senior citizens as education has become an increasingly popular way to spend retirement.

"Life expectancy has increased and people's health is better," said Jody Olsen, director of the Center on Aging at the University of Maryland. "Retirement has become more acceptable than it ever was before and people are planning for it more carefully than they ever did.

"What you have is a lot of very well educated people who have had some schooling and they want more. They have the income, they have the health and thye have the time. They know what's expected of them and they know what the challenges are and they want to do more than study arts and crafts or how to make out a will. It's a chance for them to diversify, to do something they've never done before."

For John Hoover, 67, a retired foreign service officer, the chance to take tuition-free courses at the University of Maryland was simply too good to pass up.

"Here you have a great university," Hoover said, "with a whole broad spectrum of courses, faculty, libraries and laboratories and they throw it open to any resident of the state who is over 60 years old.

"To me, that's saying, 'Here's a banquet that's been laid out for you. Take it.'"

An take it, he did.

"I very much enjoy it," said Hoover. "I find it especially stimulating to be thrown into a class with people who are young enough to be my children. They accept me as an equal and I think they are glad that I and others of my generation are in the class. We give it a dimension it otherwise would not have."

Hoover is studying gerontology -- a relatively new and rapidly expanding academic field -- and is taking several other courses related to the process of aging.

The reasons senior citizens are returning to college range from the plain old curiosity of Edgar Clark to a desire for intellectual exercise and conditioning to plans for a career change late in life.

For example, Louis E. Cotulla, a retired Army general and oil company executive, at age 75 is spending four days a week at George Mason University studying French and Spanish.

"It's something to keep me occupied," says Cotulla. "It's a way to broaden my background."

Allan Redrow, 68, who retired from a corporate practice of law three years ago, is getting ready for a new career in patent law. Since he plans to specialize in computer patents, he has been taking electronics and computer courses for the last two years at Northern Virginia Community College and George Mason.

"It's necessary to know how a computer works in order to write a patent application," said Redrow.

Almost a year ago, physician Frances Sanel, 65, quit her $30,000-a-year job in research at the National Institutes of Health to study for a master's degree in developmental psychology at Antioch College in Columbia, Md.

"I thought the time had come for me to become a human being again," said Sanel. "I began thinking about a career change two years ago. I don't know how this will turn out or where I will land, but I tell my husband at least I'll be a better wife and better human being."

For retired biochemist Bever, the paralegal program at George Washington was not only a route to finding a useful and productive volunteer activity, but also a way "to see if my mental powers and my physical powers were strong enough to absorb something completely different." Although he has suffered three strokes, Bever was pleased to discover he could, in fact, do the work.

Launched four years ago, the paralegal program is disigned to "teach people who are over 55 to be senior citizen advocates for other people who are over 55," according to program director Gottlich.

Students learn such things as the finer points of Social Security law, the details of Medicare and the many provisions of the tax and inheritance codes.

"The vast majority of attorneys in town don't know anything about Social Security," says Gottlich. "Not do they want to take a Social Security case because they know it won't pay anything.

Beatrice Aitchison, 70, completed the one-year course a year ago and has been able to use what she learned to help her friends.

"I have one friend who's going to start picking up $200 more a month from Social Security because I found out she was entitled to more than she was getting," said Aitchison. "I got widow's insurance benefits for another friend."

Aitchison is a retired college professor and postal employe. She left postal work in 1971 when the old Post Office Department became the Postal Service and has been doing some consulting work since then. She signed up for the paralegal course "because I felt I needed a little more structure in my life.

"It sounded kind of interesting. I thougth it would be fun, and it was. I learned a lot."