SAN JOSE, CALIF. -- Some enrolled because their fathers served in Vietnam and they wanted to understand their parents better. Some enrolled because they had fought in Vietnam and wanted to understand themselves better.

Whatever their motivation, the students in History of the Vietnam War at San Jose State University this past semester shared a need to learn more about the conflict that ended more than 12 years ago. By doing so, they became part of a growing national trend of treating the war as an academic topic, not just a source for family quarrels and Hollywood screenplays.

"Time enough has passed so the war can be looked at as history," said Larry Engelmann, who has taught the class at San Jose State since 1983.

A generation ago, the Vietnam war brought informal teach-ins, enormous protests and, in the case of Kent State University in Ohio in 1970, death to American college campuses. Today, the war means three credits, long reading lists, guest lectures and final exams that ask "What are the lessons of Vietnam?"

In 1980, there were about two dozen college courses in the United States devoted to the war and its effects, according to a survey by the Indochina Institute at George Mason University. By last year, that number jumped to at least 220.

Plans are in the works for a national conference this spring on teaching the Vietnam war. And next month's issue of the scholarly journal "Social Studies" is devoted to the same topic, including such articles as "Pedagogical Implications of Teaching Literature of the Vietnam War."

"Vietnam is trendy now, which is kind of embarrassing," said Carol Wilder, a professor of communications who teaches "Vietnam: Rhetoric and Reality" at San Francisco State. "But I have been teaching college for 22 years and have never seen a topic that carries such inherent interest for students. They are learning what Mommy and Daddy didn't tell them, what their history teachers in high school didn't tell them and what their culture doesn't want them to know."

The most popular course by far at the University of California, Santa Barbara, is taught by Walter Capps of the religious studies department. His topic is the impact of the Vietnam war on American society. And his technique, now copied nationwide, is to invite veterans and other participants to share memories with students.

In a recent interview, Capps discussed the popularity of his course and similar ones. "I was born in Nebraska in the mid-30s, and my father would always tell us about hard times in the Depression. I realized I couldn't understand the way I was brought up unless I understood the Depression," he said. "In much larger terms, the Vietnam war is the similar kind of event for this generation of college students -- their formative event."

Many of the professors involved are themselves veterans of Vietnam combat or protests. In astonishment at their own aging as much as anything else, they echo a common theme: Vietnam is to their students as World War II was to them.

Engelmann at San Jose State decribed his students' initial ignorance about the war as frightening. Thomas Maddux, a history professor at California State University at Northridge, who has taught aspects of the war since 1978, said many of his students at first "were lucky if they could find Indochina on a map, let alone Vietnam."

The reasons are that high school survey courses on American history usually are chronological and rarely leave much time for Vietnam. And some high school teachers report that until recently they glossed over the topic to avoid political controversy.

Some professors say the nation wanted to forget the war and its sorrows. Students say older relatives often brushed aside their questions about the conflict and its causes.

"It was a touchy subject, and everyone avoided the topic when I asked," said sophomore Stew Jenkins, enrolled last semester in a Vietnam history course at Stanford University. Jenkins said the class made him realize that the political rifts caused by the war still exist and that "if more people learned about the war, perhaps those divisions could be healed."

Classmate Rachel Marcus said: "I feel shocked that I never learned anything about it before. In high school, they sort of pushed it under the rug."

The style and content of the college courses vary widely.

There are academic approaches, such as a history course taught by Roger Dingman at the University of Southern California. His syllabus covers such weekly topics as "Imperialism: France in Southeast Asia, 1841-1941," "Mr. Kennedy's Choices, 1961-1963" and "Kissinger's Peace: Honor or Betrayal?"

Some are surveys of how the war and veterans are portrayed in movies and television shows like "The Deer Hunter" and "Magnum P.I." "Students come to understand that Vietnam veterans had been stereotyped, and they no longer accept the stereotype of the psychotic or the victimized veteran. They understand the American experience in Vietnam is much richer and deeper," said Harry Haines, an Army veteran of the war who teaches such a course at Trinity University in San Antonio, Tex.

The most unusual development in Vietnam academia is the use of guest lectures by people who fought in, planned or protested the war. This oral history has been criticized by some academics as too theatrical, biased and repetitive; those critics say more effort should be spent on researching lesser-known aspects of the war, especially from North Vietnamese sources. But defenders of the oral history technique say there is no better way to get across the passions and impact of the war.

Being in the Washington area helped Philip K. Straw organize a popular course at University of Maryland. Over the past three years, his guest speakers have included retired general William C. Westmoreland, who was commander of U.S. forces in Vietnam, former CIA director William E. Colby, American fliers who were held for as long as nine years in North Vietnamese prisons and veterans who actively opposed the war.

Awarded the Bronze Star and Purple Heart for his Marine duty in Vietnam, Straw came home from the war eager to learn more about it. He scoured the Washington area for an apt course and finally, with the help of a friend on the Maryland faculty, began his own class three years ago. "I'm an academic bus driver," said Straw, who also works full-time as executive assistant to Rep. Clarence E. Miller (R-Ohio). "I feel it is my responsiblity to take my students on a long and productive journey on what I consider to be the most critical period of American history since the Civil War."

Several veterans enrolled in the class at San Jose State said it helped them understand a central part of their lives. Political science graduate student and Air Force veteran Ed Anderson said he was based in Okinawa, Japan, during the war and helped in midair refueling of jets that he presumed were en route to bombing missions.

"I never understood why I was there," he said of his service. "This course by no means cleared everything up, but it gave me a good, objective starting point. It reinforced my opinion that we had no clear objectives in the war."