PRINCETON, N.J. (AP) _ The ''American Focus'' radio show and the college students who produce it are hardly household names, but the guests heard on the program usually are.

Jimmy Carter, Henry Fonda, Jerry Falwell, Joan Rivers, Carl Sagan, David Letterman, Bob Hope, Walter Mondale, Julia Child, David Rockefeller, Abba Eban, Dan Rather and Norman Mailer are among the hundreds of luminaries who have agreed to sit behind the mike.

The show, one of the country's largest nationally syndicated public affairs radio programs, is the work of 30 Princeton University students who have virtually no formal radio training and put the show together in their spare time.

Even radio professionals are surprised when they learn the show is just a student activity.

''It's very professionally done. I didn't know they were students. They sounded like they have been in the field for quite some time,'' said Sean Cort, public affairs coordinator for WRKS-FM in New York City, which broadcasts the program.

The weekly, half-hour show features one guest and three to four student interviewers. It boasts a network of 270 stations, including outlets in all of the nation's 50 largest radio markets.

For the most part the show is broadcast either Sunday morning or night, the time slots to which most public affairs programs are relegated.

The show is geared to adults, not college students. The program is not even heard on college radio stations.

''For the most part our audience is not our peers. It's primarily adults,'' said Richard Fitzgerald, a junior who's executive producer.

''Rock stars ... we just don't think that's what our audience will appreciate. When we do entertainers we go for the more established entertainers.''

Because a show may not be broadcast until three weeks after taping, ''American Focus'' doesn't try to break news.

It focuses on the guest's view of the news and ''a little bit about the person, their lives and things that have led them into what they are doing,'' said the show's current president, junior Sofia Perez.

But the show has made some headlines. Several years ago, actor Richard Dreyfuss admitted while on ''American Focus'' that he had used drugs. Dreyfuss also said he stopped using them after he was charged with possessing narcotics following a traffic accident.

A blown-up copy of a Los Angeles Times story crediting ''American Focus'' with the scoop hangs in the show's offices in a creeky old house on the Princeton campus.

''Sometimes, the guests, if they know we are college students, they won't put up as much as a front than if we were professionals,'' Fitzpatrick said.

The show was founded in 1974 by a local high school student who pieced the initial programs together ''with scotch tape and stuff,'' Fitzpatrick said.

The first show, with a relatively anonymous New Jersey official as the guest, could only be heard on a Trenton radio station. When the student, Garth Ancier, now an executive at Fox Broadcasting, was accepted to Princeton, he bought the show with him, initially producing it out of his dormitory room.

Today the show still doesn't receive direct financial support from the university, but it now has commercial sponsors who help pay its annual budget of $40,000 to $50,000. Money left over is put back into the program because the enterprise is non-profit.