At about 5:30 on weekday nights, when undergraduates are entering the dining halls for dinner, students at the Harvard Extension School are arriving from their daytime jobs to attend their evening classes. For the next two or three hours they listen to lectures and take notes in an effort to further their education.

They come for different reasons. An engineer from Boston comes four nights a week after spending the day designing hospital buildings. "When I went to school," he says, "I got plenty of math and science, but little else. Now I can finally learn something about the Humanities and Social Sciences. Last year I even took a course in practical composition, and now even I can understand the memos I write."

An elderly woman from Newton decided to resume her studies after taking off time to raise five children. "I got a degree in Fine Arts from Catholic University many years ago," she says, "and now that I have the time, I want to take some courses in art and literature. It hasn't been too hard getting back into the academic world, but I really won't know until my first exam."

A man in his mid-twenties works during the day as a receptionist at the University Health Services. "I study three nights a week," he says. "I've already gone to school for two years, so if I can keep it up here for a couple more years, I'll be able to get my degree."

The health receptionist is one of 250 degree candidates among the 6000 students enrolled in Harvard's Extension School. Founded in 1910 by a grant from Boston's Lowell Institute, the extension school has grown from a small program tailored to the needs of Boston teachers who wanted certification to a community-wide educational facility. The extension school now offers 136 courses and, after the College, has more students than any other division of the University.

The school's instructors are members of the faculties of seven local universities, with about half from Harvard, including many full professors. Extension students can attend many courses identical to those offered to undergraduates at Harvard or MIT or Boston University and pay only a fraction of the price, as tuition per semester course ranges from $20 to $40.

Students can work toward an Associate in Arts degree by taking eight courses over two years or, if more ambitious, they can aim at the sixteen-course Bachelor of Arts in Extension Studies, which often takes up to eight years. Most students, however, are not working towards a degree and take courses merely out of interest.

Despite the accessibility of extension courses in terms of cost, the school no longer attracts as diverse a student body as it once did. Even in terms of age, which would seem an intrinsic basis of variety in an adult education program, the extension school is becoming more homogeneous.

"The average age of the students is much younger than it was when I started with the extension school in 1949," says Reginald H. Phelps, dean of the school. "The student body looks more and more like an undergraduate school." He attributes the younger age of students to recent tendencies to drop out of school and to take time off to work after graduation. The extension school, he says, provides a haven for such people, if they want to return to the academic world.

Part of the explanation for the lack of diversity among extension school students probably lies in the orthodox nature of the courses offered. Many of them are facsimiles of the courses faculty members offer their undergraduates, and Harvard students flipping through the extension catalogue would not immediately realize they had strayed from their oft-perused Courses of Instruction.

The close connection between course offerings and student composition is borne out by Extension School experiments to attract broader sectors of the community. The school sponsored a Training Teachers of Teachers program given two years ago in Roxbury that enabled residents of that neighborhood to fulfill requirements for teacher certification while pursuing an A.B. degree.

Faculty at the Extension School view their interaction with the student body there in different ways. Some, like George W. Goethals, lecturer on Social Relations, who offers "Clinical approaches to the Study of Personality," sees little difference between the satisfaction of teaching at the Extension School and at the College. "They are a very different group, of course--second-chancers and people studying out of sheer interest," Goethals says. "But I find the students very interesting--not at all less stimulating than undergraduates." Goethals says that the great variation in abilities among Extension School students only makes teaching them all the more interesting. But "Reactions to the material are generally the same" as those of undergraduates, he says.

On the other hand, Martin L. Kilson, professor of Government, says that he is attracted to the Extension School because it offers a "broader intellectual and social experience than that associated with being an academic." Kilson, who is offering "Ethnic Politics in America" in his twelfth year of extension instruction, says that he is "hooked" on teaching extension courses because the "far more variegated background" of the school's students "brings an added dimension to discussions."

"For example," Kilson explains, "the kinds of examples students produce to elaborate an argument or to explain a point is very different from the intellectual's examples. It's much more out of the stuff of lower-class and middle-class working people. For instance, there have been policemen in my class. Their knowledge of politics is unique--it adds to my own grasp of conflicts in urban political life."

Perhaps future expansion here should be directed toward the Extension School, so that larger sectors of the community can reap the benefits of continuing education. The success of such a venture would depend on the willingness of Harvard's administration to give some financial support to the school, which at present operates solely on the basis of tuition and a small grant from the Lowell Institute.

If, however, as Kilson claims, and as others in continuing education would surely agree, adult education has an added dimension about it, a richness lacking from undergraduate instruction in which the student body is markedly homogeneous in terms of age and social background, then perhaps Harvard educators should study extension school education more closely with the idea of integrating it into the College. Maybe only when people such as the policeman in Kilson's course are present in the undergraduate classroom will college discussions take on the edge of reality they now so often lack.