Whatever else any great American playwright has done, each one has created, and in turn become identified with, a personal vision of the American family. If anything, the measure of achievement in American drama has been a writer`s ability to place a vivid family portrait within a larger, societal frame or, more to the point, to make the family represent not only the writer`s inner life but a set of outer conditions.

One thinks of Arthur Miller`s men, hustlers who lived through one Great Depression and live in fear of another; of Tennessee Williams` women, cut loose with the fall of the plantation aristocracy and thrown into the cruel cities. O`Neill, Odets, Inge, Albee, all conjure images of the family at war with itself.

And in a cycle of family plays stretching over a decade--and culminating with the opening of the newest one, "A Lie of the Mind," recently at New York`s Promenade Theater - Sam Shepard has painted a picture of domestic disharmony as striking as any to have preceded it. The wastrel father of  "Curse of the Starving Class," the Cain-and-Abel brothers of "True West," the incestuous lovers of "Fool for Love" have become indelible characters in the contemporary American theater.

So, too, has Shepard staked his claim to the landscapes, both geographical and psychological, of the rootless American Southwest and the beleaguered Middle Western farm belt.

The elements of Shepard`s mythology coalesce again in "A Lie of the Mind." This sprawling play runs about four hours and follows two families, one in Montana and the other in southern California, that are bound by the brutal marriage of two children. In its vast scope and in several of its themes - possessive and violent love; guilt, escape and lies -  "A Lie of the Mind" resembles Shepard`s screenplay for "Paris, Texas" more than his recent plays. The film version of one of them, "Fool for Love," opened recently with Robert Altman directing and Shepard starring.

As Don Shewey points out in his recent biography of the playwright ("Sam Shepard," Dell Books), Shepard`s cycle of family plays departed from his earlier work. Shepard lived and wrote amid the East Village's experimental theater movement, and from 1963 through 1976 his plays tended toward the fantastic and his creations included cowboys and rock stars, bayou monsters and B-movie gumshoes.

Then, with "Curse of the Starving Class," Shepard began to penetrate his own past and to work in an increasingly naturalistic vein. Each play since then has peeled back more layers of the playwright`s itinerant upbringing and, particularly, of his relationship with his father.

"I don`t think it's worth doing anything," Shepard said in a recent interview, "unless it's personal. You're not dealing with anything unless you`re dealing with the most deeply personal experiences."

Still, Shepard acknowledges the transition in his work since "Curse of the Starving Class." "I thought for years it was boring, uninteresting to write about the family," he said. "I was more interested in this thing of being wild and crazy. But the interesting thing about taking real blood relationships is that the more you start to investigate those things as external characters, the more you see they're also internal characters. The mythology has to come out of real life, not the other way around. Mythology wasn`t some trick someone invented to move us. It came out of the guts of man."

The presence that looms over Shepard's recent work - and, one would surmise, over his life - is that of his father. Samuel Shepard Rogers died in 1983 when he was hit by a car near his home in Santa Fe. His death left forever unresolved the influential and often volatile relationship with his son. Their torturous bond permeates both "A Lie of the Mind" and the film "Fool for Love."

Shepard has created two fathers in "A Lie of the Mind," each with apparent echoes of his own. One lives with his family in Montana but longs to leave, blaming his wife and daughter for ruining his life. The other father is never seen onstage. He deserted his family, the audience learns, and went to live in a house trailer. Stumbling drunkenly along a highway after a drinking contest with his son, he was hit by a truck and killed - a death, needless to say, with some parallels to the real Rogers'.

In the film of "Fool for Love," the character of The Old Man, the common father to the lovers Eddie and May, assumes an even greater importance than he did in the original stage version. There, The Old Man sat on the side of the stage, sipping whiskey and occasionally speaking. The Old Man of the film is a constant, active presence - a "Twilight Zone"-style gremlin or some kind of malevolent puppeteer.

Sam Shepard`s actual "old man" was an even more complicated character. A World War II flyer (like the offstage father in "A Lie of the Mind"), he attended college on the GI Bill, read Lorca, Neruda and Vallejo, taught high school geography and Spanish and studied at the University of Bogota on a Fulbright scholarship. He could be a beguiling teacher at school and storyteller at home. He also was an alcholic, a father who fought bitterly with his son, a husband who frequently vanished from his family.

"It was hit and miss, always hit and miss," Shepard`s sister, Roxanne Rogers, remembers of the relationship between the playwright - who left home when he was 19 - and his father. "There was always a kind of facing off between them and it was Sam who got the bad end of that. Dad was a tricky character. Because he was a charismatic guy when he wanted to be - warm, loving, kind of a hoot to be around. And the other side was like a snapping turtle. With him and Sam it was that male thing. You put two virile men in a room and they`re going to test each other."

"A Lie of the Mind`` has brought Shepard back to New York, his first home away from his family and the scene of his early triumphs. Here he formed part of a downtown theatrical community that also included the playwright Lanford Wilson and the producer Ellen Stewart, among others.

"There was this big fight with my old man," he recalled in a recent Newsweek interview, "and at that point I fled. And I thought, well, I`m just going to have to start over, pretend I don`t even have a family." Rogers remembers that their mother Jane was sure Shepard would succeed as a writer, but that their father remained skeptical. He saw only one of his son's plays, and the occasion typified the picaresque and pathetic nature of his life.

"Once there was a production of 'Buried Child' in Santa Fe," Shepard said, "and my Dad took it upon himself to go, and he was rolling drunk and started talking to the characters and stood up and made all this noise. He definitely struck up a relationship with the production. When the audience finally found out he was my old man, everyone stood up and gave him a standing ovation. He was in a state of shock."

As he became a husband and a father, as he advanced into middle age - he is now 42--Shepard sought reconciliation with his father. Sometimes the effort took the form of writing, such the speech in "Buried Child" in which a teenage boy, Vincent, tells of looking in the mirror and seeing his face turn into his father's. Sometimes it meant father and son going out drinking together.

Yet Shepard is more elegiac than angry when he talks about his father's death. "It hasn`t really clarified anything," he said. "Nothing's clearer to me. You spend a lot of time trying to piece these things together and it still doesn`t make any sense. His death brought this whole thing to a head, this yearning for some kind of a resolution which could never be. But at the same time, it was well worth the journey, trying to make some kind of effort to re-establish things.

One consequence of the turbulent Rogers household, and of Rogers's death, is that it made the children hunger for family. "I think it gave us a concrete perspective of what we had as a family, that it wouldn`t be around forever," Roxanne Rogers said. "We've always been spread around and kind of carefree in our relations. What happened is we decided to try to put this family back together."

Rogers herself is working as the assistant director of "A Lie of the Mind." The other daughter in the Rogers family, Sandy, wrote and performed eight songs for the "Fool for Love" soundtrack.

"My work has always come out almost like a miracle, some kind of strange accident," Shepard said, discussing new expectations of his work. "You stumble into a certain territory that starts to excite you in a way that`s got to be manifested. It comes out as a play or a character. But that kind of work cannot be formulated by 'My next project is this' or 'They're expecting me to do this.' Then it gets shot to hell. Because then it becomes a career. I'm not interested in a career. I don`t want to have a career. I want to do the work that fascinates me."