"Every year, I write down on a slip of paper the name of the play that I think has the greatest marketplace value," admitted Jon Jory, the producing director of The Actors Theatre of Louisville (ATL), which for the past six years has hosted an increasingly ambitious festival of new American plays. "And do you know something? I've been wrong every time."

If Jory, an affable man who resembles a neatly groomed bear, is telling the truth, that means he was wrong about "The Gin Game," which turned up in the first festival in 1976, and then went on to Broadway and a Pulitzer Prize. It also means he misjudged "Getting Out," the hit of the second festival and a subsequent off-Broadway triumph; overlooked "Crimes of the Heart," which emerged in the third festival and snagged last year's Pulitzer; miscalculated on "Agnes of God," which came out of the fourth festival and just opened on Broadway last week; and was not all that certain about "Extremities," the shocker from the fifth festival, which is scheduled for New York production later this season.

It could be, of course, that Jory was merely defending himself ingenuously from the accusations born of his shining success. ATL's yearly festival--officially dubbed "The Humana Festival of New American Plays" after the Louisville-based hospital services corporation that puts up most of the cash--was founded to encourage playwriting, not to stock the entertainment industry with wares. But there's nary a producer, agent, artistic director, movie executive or television scout alive who hasn't realized by now that Louisville in the spring is more than fields of sprouting blue grass. Jory's disclaimer that he wouldn't know a long-run from a fast-flop hasn't prevented the festival from becoming, among other things, a big brawling marketplace.

The list of those who poured into Louisville last weekend for the sixth festival--a three-day bash of plays, hand-pumping, contact-making and general reconnoitering--ran to seven single-spaced typewritten pages. It included representatives from three cable networks, the Abbey Theatre in Dublin, Universal Pictures, Jujamcyn Theaters, the National Endowment for the Arts, National Public Radio, the Kennedy Center, the William Morris Agency, the State Theatres of Turkey, the Swiss Broadcasting Corp., Walt Disney Productions, Nederlander Productions, Paramount Pictures and the "Today" show. There were also 59 critics--one of whom was filing for the Xinhua News Agency, which serves the Republic of China; another who'd flown in from London and repeatedly voiced his desire, during intermissions, to "see Indiana."

"It's getting just a little predatory around here," remarked one guest, nervously eyeing the throngs that jostled their way into ATL's two-theater complex early in the morning, and then jostled their way back out, usually around 11:30 at night for a final round of hard drinks and soft soap at the Starving Artist Bar. What ATL offered them this year was: three one-act plays, four full-length plays, two "Nicholas Nickleby"-style adaptations, and no fewer than 18 monologues, which prompted one bleary-eyed spectator to quip afterwards, "I'm monologged."

The festival's slogan, emblazoned on red-white-and-blue buttons worn by an indefatigable staff, proudly hailed "The New Write." By the end of the weekend, however, it had taken on an unintended irony, underlining the essentially conservative nature of the playwriting on display and a preoccupation with the roots, the land and small-town folk clinging fitfully to traditional values. By general consensus, the most popular offering was Lee Blessing's "Oldtimers Game," a lively comedy about bush-league baseball players who are trying to weasel their way up to the majors. Set in a locker room and populated with nine distinctly drawn characters, it takes great sport with the national sport. But unlike David Storey's "The Changing Room," to which it bears some resemblance, it doesn't probe very deeply, and onewas sorely tempted to view it as a play auditioning for a TV series.

There were certainly fewer pleasures to be gleaned from the two adaptations--a relentlessly melodramatic regurgitation of John Steinbeck's "The Grapes of Wrath" with a Ma Joad who proved less a tower of strength than a stump of stubbornness; and a murky recounting of Liam O'Flaherty's dark novel of the Irish underground, "The Informer," performed with a variety of thick accents that eluded even the critic from The Irish Times. There was a lesson, however. The effortless art of a "Nicholas Nickleby" is not easily imitated, although the American theater now seems to be in for a long siege of home-grown Nicklebies.

Rural America dominated the remaining full-length works. John Olive's "Clara's Play" explores the bonds between a batty Minnesota recluse, circa 1915, and the itinerant Norwegian laborer who helps spruce up her farm before the bank forecloses on the property. In Ara Watson's "A Different Moon," a Georgia bumpkin comes seeking solace from the family of the young man who impregnated her before skipping off to the war in Korea. And in Conrad Bishop and Elizabeth Fuller's "Full Hookup," a psychotic drifter bashes his wife to death with a frying pan in his mother-in-law's trailer, then moves in with mommykins and apparently becomes the apple of her unsuspecting eye. In the measure that the festival provoked any controversy, the emotional and physical violence of "Full Hookup" provided it. One New York agent, baffled by the obliqueness of the characters' motivations and queasy from the on-stage blood, asked loudly, "Whatever happened to sophisticated comedies set in Manhattan penthouses?"

If the "Nicholas Nickleby" syndrome was predictably at work, the festival gave equal time to the opposite end of the spectrum--the modest monologue, running from seven to 25 minutes. The most distinctive, grouped under the title "Talking With," were written by Jane Martin, who scored a huge success at last year's festival with her maiden effort, "Twirler," the odd and oddly mesmerizing defense of the art of baton-twirling by a spangled teen-ager. Martin's is a unique sensibility. It mixes a kind of primitive religious ecstasy with a cutting anger and a disturbing surrealism. Her characters--females only--are bizarre, maimed creatures, yet in a way, they are also quite ordinary in their extraordinariness. Lily Tomlin sometimes ventures into this strange territory (remember Crystal the Terrible Tumbleweed, the 35-year-old quadriplegic who yearns to go hang-gliding?). Martin's gallery encompasses a gracious matron who spends her days in a rented loft, overflowing with lamps, which she turns on and off, reveling in the changing patterns of light, the emanations of heat, "the memories"; a Pentecostal teen-age snake-handler who gets to "wonderin' if people got anything in 'em could lock a snake's jaw"; a pregnant woman in the throes of birthing a dragon; and an elegant sophisticate who coolly displays the tattoos on her body, each one corresponding to someone in her life who "marked" her.

Martin has, as they say, "a voice." Few, however, know whose it really is. Jane Martin is a pseudonym. The script for "Twirler" appeared--unsigned--on Jory's desk one day, and even after it galvanized audiences at last year's festival, Jory remained unaware of the author's identity. She has since revealed herself to him but, wary of outside pressures, prefers to preserve her anonymity. The program identifies her merely as "a Louisvillian." She--if she be a she--presumably works at the theater. But Jory resists any further inquiries. "Frankly, I don't know if this person will ever come out of the closet," he said.

Since her pieces were by far the most original offerings in this year's festival, more than a few agents grumbled with frustration, as if a door had suddenly been slammed on their acquisitive fingers. Meanwhile, the other playwrights were courted and cajoled with varying degrees of duty and enthusiasm. Those that weren't simply reversed the process, and went after the agents and producers themselves. "This is where the real action is," marveled one West Coast critic at a mid-festival party. "It's like Sunset Strip here, a real meat rack." Then with a trace of dismay: "The only redundant ones are the critics. No one knows what to do with them."

Just what promises are actually made--and kept--in the course of the weekend is difficult to know. Mark Stein, a 30-year-old Washington playwright who broke into the festival this year with a one-act, "The Groves of Academe," acknowledged the "Cinderella element" that now seems part of the festival's permanent mythology. "I was forewarned by the staff," he said. "They told us to look out for this weekend. Don't go committing yourself. A lot of people have come up to me and said, 'I'll be in touch.' But I consider that kind of gracious."

Stein's experience probably comes closer to the real purpose of the festival, obscured as it may be by the hurly-burly. He has had three full-length dramas produced by the industrious New Playwrights' Theatre in Washington, but ATL represents his first real brush with an Equity company and national exposure. As a result, "Groves"--a warm, mildly autobiographical account of a rambunctious college student and the English professor who guides him through a thesis on comedy and also teaches him a few lessons about life--will be published by the Dramatists Play Service. And the Manhattan Theatre Club has optioned it for possible production in the fall.

Mostly, though, working with professionals--and being observed by them--has given Stein a big psychological boost. "This last year, I've had a growing frustration, in that I felt my craft was there, but the recognition wasn't forthcoming. Being promising at 30 wasn't enough. I came real close to looking for exits from this profession. I don't know if having a one-act play here can get things rolling for me, but I finally feel as if I have a foot in the door. If nothing else, it's certainly swelled my Rolodex."

The tendency, of course, after five years of reasonably heady success, is to make the sixth festival more than it is--both a barometer of American playwriting and a launching pad hurtling next year's Pulitzer winners into orbit. The UPI critic arrived to discover his rave from last year--"Today, all theatrical roads lead to Louisville"--reproduced on orange T-shirts, and the Louisville Courier-Journal noted in a spirit of hometown boosterism that for one wondrous weekend, at least, Louisville was the theatrical capital of the nation, "if not the world." Lest history be lost, a local documentary crew was on hand to commit festival highlights to video tape.

Still, most of the horse-traders went home more or less empty-handed, and if the sundry works they viewed revealed anything conclusive about playwriting today, it's simply that there's a lot of it going on. ATL's literary department received some 4,000 scripts for consideration this year. The final choice falls to Jory, however, and probably reflects his personal sensibilities more than those of the country at large.

"All I can do is what I have affection for, what attracts me," he reflected during a rare moment of quiet grabbed on the run. "I don't know how else to work. I'm not naive enough to think that show business is not a business. I suppose that if no one liked any of the plays here, in a very short time we'd be in difficulty. But the pressures on me tend to lessen each year, because I realize that I'm reduced to intuition. I'm not afraid of past successes, and while I'm not rich in years, I've taken my share of beatings and will take more in the future. But I still get an enormous amount of pleasure out of doing this one thing. The festival breaks our isolation, allows us to dance with our peers, and provides us with a shot in the arm."

The logistics are staggering and ATL augmented its paid staff by 50 (to 150) simply to handle the backstage complexities and keep visiting egos salved. As a rule, the productions were of a measurably higher quality than the plays themselves, and the acting consistently solid. Anne Pitoniak, for one, performed the rather dizzying feat of playing, in succession, the lamp-lady in Martin's gallery of the injured; a bed-ridden senior citizen grappling with loneliness and constipation in the one-act "The New Girl"; the suspicious Minnesota pioneer in "Clara's Play"; and the misguided mother who takes her daughter's murderer to her bosom in "Full Hookup."

Joe Dowling, the artistic director of Dublin's Abbey Theatre, admitted that he was suitably impressed by the professionalism of a regional theater that could deliver 27 plays, not to mention hundreds of box lunches, on such a tight schedule. "But you know the real reason we're all here?" he said. "Broadway!"

One of Martin's monologues also speaks to that point. It is delivered by a disenchanted female cowpoke, who finds herself bumped from the new, fancy-pants rodeo, choreographed and "Ice-Capaded" for the masses. You've got to be careful these days, she warns. There are folks out there who'll repackage your experience and peddle your fun at the drop of a dollar sign.

Actors Theatre of Louisville, take note.