WILLIAM GRAHAM, chairman of the Catholic University drama department, has spent a lot of time on the phone these last few weeks, trying to round up alumni for today's reunion of former CU stars.

A lot of alumni aren't coming.

Helen Hayes, Jon Voight, Henry Gibson, Ed McMahon, Frances Sternhagen, Lawrence Luckinbill, Susan Anspach, Jason Miller, Michael Cristofer, Alan Schnelder, John Heard, Walter Kerr and Ernest Thompson can't make it.

The reasons vary, but their basic problem is, well ah, success. In a profession whose unemployment rate rivals that of downtown Calcutta, an astonishing number of CU's one-time students and teachers of drama have found gainful and attention-getting work.

But the absence of the big names won't stop anyone from telling stories about them. It will only enable Graham and Father Gilbert Hartke, who has been the mainstay of theater at CU for 40 years, to tell their most cherished tales as they like them told, without fear of contradiction from any of the participants.

Ed McMahon, for instance (who can't leave Los Angeles because it is "sweep week," in the Nielsen ratings), will be unable to dispute the account of how his infant son let out a terrific wail in the middle of one of Father Hartke's classes, prompting the professor to comment: "That's the most intelligent remark I've heard from any of my students."

Nor will Jon Voight be around to quarrel with the description of him as "the best baby-sitter we've ever had" but a "not especially talented actor" and, when it came to working on the stage crew, a virtual incompetent.

And Susan Sarandon will not get to hear Father Hartke recall how remote the prospects seemed for "that skinny kid ever making it anywhere . . . She was so skinny the eyes were popping out of her head."

It's not that CU "turns out" skilled theater people, cautions Leo Brady, who has taught playwriting there for over 30 years. "Whatever institution says they turn out really attracts . . . We can only claim that we don't interfere with their advancement."

Graham, who has taught acting at CU for over 20 years, says he has had only one student in all that time whose promise was unambiguously evident in the classroom. That was John Heard, star of the movies "On the Yard" and the upcoming "Heart Beat," in which he plays Jack Kerouze. At first Heard was "so intense about doing it right he wasn't giving himself permission to do it freely," says Graham. "I said, 'John, play the scene so that everyone out here will say you made an ass of yourself.'" That instruction, Graham adds, made the difference.

Richard Bauer, a member of the Arena Stage company for the last 13 years, was a graduate student in drama at CU in the mid 1960s and says, "I really believe in those people. I think they're neat . . . I still look for people like the people I knew there."

Two years ago, Bauer was working for Joseph Papp in New York and one day, he recalls, "Mr. Papp said very delicately, "You're fired." That experience - the first time it has happened to him as an actor - so filled Bauer with doubts about his skills that, he says, he spent the summer working again with Brady, Graham, and James Waring, another CU teacher who now runs the CU-owned Olney Theater.

When Bauer arrived at CU from St. Louis in 1962, he was sent to the speech clinic for routine testing and informed he would have to continue reporting there regularly to correct a defect in his pronunciation of the letter "s." "You could not make your degree if you didn't clear the speech clinic," he says. "I was deeply embarrassed by the whole thing but then I thought, that's just one more reason for believing these people know what they're doing."

Many CU alumni, like Beuer and has wife Halo Wines (whom he met there and who now also acts at Arena), left without abtaining a degree. Their interest was the training, the chance to act and the chance to be seen (and the training, a few of them frankly admit, took a back seat to considerations two and three).

Frances Sternhager, a Tony Award nominee this season for "On Golden Pond," enrolled at CU after an unsuccessful audition for Arena Stage's Zelda Fichandler in 1952. "I don't audition well," says Sternhagen. "She said politely, 'Well, when there's something we'll call you.' But I knew if I got on a stage, if I could get someone to come and see me I'd have a better chance." At CU, she did "The Skin of Our Teeth," directed by Alan Schneider, and sure enough, Fichnadler came to see her and Sternhagen soon went to work at Arena.

"I loved the atmosphere there (at CU)," says Sternhagen. "They're very warm and their standards are high."

Coincidentally, Barbara Andres, who plays the daughter in "Golden Pond," decided to study at CU after seeing Sternhagen act at Olney in Clifford Odets' "The County Girl."

Yet another "Golden Pond" participant, it's author, Ernest Thompson, took a course at CU for the single ulterior motive, he admits, of making himself eligible to audition for guest director Cyril Ritchard, he was to do a production of "The Pleasure of His Company." The ploy worked. Thompson was the last student to audition for Ritchard, but got the part, and later toured with Ritchard in "The Devil's Disciple," the break that gained him admission to Actors' Equity and began his career in earnest, he says.

Thompson, whose acting career has been "resting" since he began writing plays, thinks the root cause of CU's theatrical accomplishments is Father Hartke. "You has a rather aggressive dynamo of a person, some good people drawn there immediately and it just snowballed over the years," says Thompson.

Bauer describes Father Hartke as a "wonderful man" but adds that people frequently misjudge him for "one of the most silly asses you ever met in your life . . . a piece of fluff." Michael Todd, the late producer and husband of Elizabeth Taylor, once gave Hartke an expensive overcoat (the proverbial coat off his back), because it was a cold night and Hartke was seriously under-dressed. "He's a beggar from the word go, but he's one of the most successful, high holy beggars you'll ever meet," says Bauer. "And he turns around and gives the money away."

Father Hartke, now 72, likes to describe himself as being in his "anecdotage," but also notes that "I look more like Robert Redford than Marion Brando."

After he founded the CU drama department couldn't otherwise match the money he was earning from radio scripts for Quaker Oats and Aunt Jemima, Hartke's as well (Kerr never knew about this at the time, says Hartke). Another member of the original faculty was Josephine Callan, who died last year at the age of 95 and whom Kerr describes as "the greatest acting teacher and voice teacher that I ever came across."

"The pieces just fit together very beautifully," says Kerr, "so that there was a functioning team after a year or two that lasted for seven or eight years."

Kerr and Brady became a team of their own, too, collaborating on a series of original plays that helped establish CU as a place to see theather as well as study it. During the 1940s, Kerr recalls, Washington theater meant the National Theater, and since "there was no point trying to duplicate what they are doing." CU began offering a mixture of classic and student-and-faculty-written originals - "though to be death at the box office," says Kerr.

Soon the Audience for such productions as the Kerr-Brady "Yankee Doodle Boy" (based on the life of George M. Coban) had built to the point that runs had to be "chopped off after a while," according to Kerr, just to allow the participants to get on to other things.

In the '50s, CU began an era of empire-building, founding the National Players (a touring company largely composed of its students and alumni, operating a summer theater in St. Michaels, Vt., for 20 years, and assuming control of Olney Theatre, whose then-owner, C.Y. Stevens of the Highs Store chain, was dissatisfied with what the previous Olney management had been offering.

The National Players, still in business 30 years later, will have a reunion at the Hartke Theater this afternoon. And tonight, at Olney, there will be a benefit performance of "Joseph and His Technicolor Dreamcoat" (tickets available at the box office, says Graham) to establish undergraduate and graduate scholarships in acting, directing and designing.

With any luck, CU hopes to produce yet another generation of stars who, years hence, will fail to show up at their reunions, too.