Near northern California's Marin County hills, the playwright-actor Sam Shepard leads a deceptively quiet life, sharing a modest suburban hacienda with his wife, O-Lan, their 11-year-old son, Jesse Mojo, O-Lan's mother and stepfather and four dogs. The 1979 Pulitzer Prize winner for drama favors this isolated "sphere of reference" - playing drums with a local jazz group and hauling his sorrel quarter horse to the rodeo in Santa Rosa in his custom Ford pickup. The former resident genius of Off Off Broadway, whom some critics have hailed as the best practicing playwright in America, has become a fair true-to-life cowpuncher when he is not away working on a Western movie.

"I don't go to the theater - I go to the rodeo, go to the track a lot, too - I guess you could say my cultural appetites are kinda narrow," Shepard says in a cagey Western drawl during a lunch break from a rehearsal for the world premiere of "True West," which will have its New York opening at the Public Theater next month.

He has put off a rip to see his acting agent in Los Angeles to sit, benignly vigilant, in a rear row of San Francisco's Magic Theater, his tooled cowboy boot draped over a knee, offering suggestions when asked for them and chuckling occasionally at an actor's well-time delivery. Friendly, unassuming, Shepard nevertheless has a habit of avoiding a stranger's eyes. He is naturally wary of journalists and gives few interviews. Writing plays, he tells me, "isn't something you talk about. It's something you do." He would rather talk about head-roping steers.

"You know," he says, "the rodeo's a pretty weird setup. There are actually ranch hands who do this sort of thing for a living up here. Then come the sports guys, like me, who come in half-cocked. Or these T.W.A. pilots who go to get their hats knocked off and stuff."

Shepard's five-year relationship with the Magic - a small, third-floor theater in Fort Mason, a former naval facility now turned alternative culture center - seems to suit his temperament ideally, removing him from the competitive pressures of the New York theater. In this theatrical homestead, his plays are animated by a single creative tension: the struggle between his wish to find a home in the contemporary wilderness and the opposing urge toward a pure, unfettered freedom. Shepard has no plans to attend the Public Theater production of "True West". He will not set foot in a plane, and depsite seven years in Manhattan in the 1960's and early 1970's, he never thought of it as a place anybody would call home...

After high school, Shepard enrolled at a local junior college, but ended his formal education three semesters later. He was about to take a job managing a sheep ranch when he joined a repertory theater touring the nation's churches. He needed to get out of Duarte: His family was tearing itself apart from the inside.

He lasted only a few months on the tour. By the spring of 1963, he was sharing a cold-water flat in the urban badlands of Manhattan's Avenue C with Charles Mingus, Jr., an old high school friend. The son of the legendary black jazz artist helped Shepard land a job using tables at the Village Gate three nights a week, leaving Shepard free to wander the streets with Mingus, literally pretending to be a cowboy in what Norman Mailer calls "the Wild West of American night life." Soon fafter his arrival, he changed his name from Steve Rogers to Sam Shepard, "because it was shorter."

In early 1964, a fledgling theater at St. Mark's-in-the-Bowery was looking for new playwrights. Shepard offered them "Cowboys", a rowdy Beckettian western based on his street adventures with Mingus. The persona of the cowboy was largely a fiction at this point, a romanticization of his rural life in Duarte. The only exposure he'd had to "real" cowboys was "seeing Leo Carrillo, the Lone Ranger and Hopalong Cassidy in the Rose Parade."

"Cowboys and a second play, "Rock Garden," ("about leaving my mom and dad"), opened Theater Genesis's first season in the fall of 1964. The daily papers slammed the plays as bad imitation of Beckett, but Michael Smith of The Village Voice gave the 20-year-old newcomer a rave notice. Without that review, Shepard probably would have packed it in for California.

Shepard's recognition as one of the finest talents of the new Off Off Broadway theater came about remarkably swiftly. Churning out one-act plays by the dozen, he won two of The Village Voice's Obie awards for Off Broadway and Off Off Broadway theater within three years. In 1966, he garnered the first of many academic productions at the University of Minnesota; Yale and Princeton produced new works in later years. In 1967, he spent his first grant, a Rockefellar, on a Dodge Charger and a classic Stratocaster guitar.

In the mid-1960's, Shepard became the drummer for the Holy Modal Rounders, and wrote the first of several rock-influenced plays. The Rounders, basically an "amphetamine" band, drew Shepard more deeply into drugs - a part of his New York life style and free-form writing habit from the beginning. He escaped the draft in 1965 by pretending to be a heroin addict.

In the summer of 1967, Shepard completed his first full-length play, "La Turista," written in Mexico under the influence of amphetamines and dysentery. One week into rehearsals in New York, he replaced the last two acts with a single act - the first time, he says, he had ever rewritten anything. "La Turista" caused Elizabeth Hardwick, in The New York Times Review of Books, to call him "one of the three or four most gifted playwrights alive."

"La Turista" signaled the beginning of the end of his enchantment with Off Off Broadway. Theater became a job and Shepard responded with some of the most outrageous plays of his career. A major work for his first "uptown" audience, "Operation Sidewinder" (1970), proved a critical catastrophe, with subscribers to the new American play series at Lincoln Center canceling in droves.

Under the pressure of growing notoriety and an increasing drug problem, Shepard fled New York "for good" in 1970 with his wife, O-Lan, an actress and fellow Californian whom he had married in 1969, and their 2-year-old son. He moved to England, hoping to get into a rock-and-roll band.

"It was incredible luck to be around when something like Off Off Broadway was getting off the ground," recalls the ear's brightest star. "But the 1960's were kinda awful. I don't even want to think about it."

Shepard claims he learned two things in England: how much work it takes to make good theater, and that it might mean something to be an American.

The family survived at first on meager royalties and grants. Staying for a time in Shepard's Bush in London, he began a new three-act play set in a jail. Buring what he had written and starting over, he swiftly completed a new version set in an unrecognizable space and time, which became "The Tooth of Crime", still considered by some critics to be his finest work...

Despite what some critics took to be a nearly perfect union of metaphor and language, "Tooth" appalls Shepard today: "You don't want to mess with people's psyches like that. I sure did mess with mine. You just don't want to heave a bunch of baboons out in the street. People are crazy enough. I'm not denying it, though - it's there for anybody to read the damn thing."

Most of Shepard's work in London was of a less sinister nature. He never made it into a rock band, for he was given free rein at the Theater Upstairs at the Royal Court, where he directed for the first time. Working with actors he considered among the finest in the world, he began to ascribe most of his "so-called originality" to ignorance. The director Peter Brook saw one of his plays and, Shepard recalls, "he told me I should start thinking about character more.

With an increased sense of discipline and possibility, Shepard and his family returned to the West in 1974 "to find our roots." They moved in with O-Lan's mother and her new husband in a Northern California tract home never Corte Madera - "the kind of place with paisley felt wallpaper in the bathroom," recalls a friend. Shepard took a three-year lease on a nearby 20-acre ranch, the Circle Y, not to live there but to raise appaloosas. Soon afterward, they moved to their present home, where Shepard writes his plays in longhand on yellow pads before typing them on a battered Austrian manual. He has not touched drugs or seen the Empire State Building in five years.

Shepard has found a new contentment in the West, but his Americanism has always run deep beneath his unruly pop mythologizing. Fascinated by violence and embarrassed before life, his theater proceeds from a vision of radical innocence, a surrender of identity to the mysterious power of mythic blood...

"I used to be a lot more interested in situations," Shepard says, "or just the sound of words, and what that did to characters. Characters seemed like a corny idea, a narrow reference. Now I'm interested in character on a big scale."

I ask him why he wrote "True West".

"Does it change the perception of the play if I don't answer that?" Shepard says, but answers anyway:

"I wanted to write a play about double nature, one that wouldn't be symbolic or metphorical or any of that stuff. I just wanted to give a taste of what it feels like to be two-sided. It's a real thing, double nature. I think we're split in a much more devastating way than psychology can ever reveal. It's not so cute. Not some little thing we can get over. It's something we've got to live with.

"I worked harder on this play than anything I've ever written. The play's down to the bone. It opens up new ground for me. I can see a lot of new directions. It's human ow. One-to-on. I was real embarrassed by 'Buried Child' - lot of toe-scrunchers in there. That's why I dig the Greek myths, like 'Oedipus Rex.' This devastating harm coming down from the heavens. No Jung, no Freud, any of that. No 'language' or trappings at all. Now that's a story."Shepard missed rehearsals only once in a while; one night he arrived late in a new G.M.C. pickup, big enough to haul the horse trailer to his next movie location, in Maxwell, Texas. In "The Raggedy Man," Shepard plays a disabled World War II veteran who returns hom, unrecognized by his wife, played by Sissy Spacek, the wife of the film's director, Jack Fisk.

We took off into the cool San Francisco night, past the drugstores and restaurants on Chestnut Street, heading for a bar, sharing tales about growing up in California - a place he hardly recognizes anymore. Developers bought the Circle Y out from under him two years ago.

"There is a fact of experience here that only a few people understand," he said softly. "It's more diffused now, since there are so few true Westerners. But still there are places here where people are really part of the land. The place you come from influences everything. The fact that Pablo Neruda was a son of the jungle is to me me what makes him a great poet. He never lost his perspective. Now artists are wiped out in the same way as everybody else. They're cut off from where they come from."

Nostalgia and discovery sometimes appear as similar emotions. The great American playwright may be an impossibility these days, but it may be safe to call Sam Shepard the playwright laureate of the West: consistently, ruthlessly true to his experience of a wilderness where America has always hidden its promise and its dream.