It used to be a joke--theater in Los Angeles. Like higher learning in Little Rock. If this sprawling, palm-studded metropolis evinced any interest at all in live drama, it was as material to be converted into celluloid. Theater was an East Coast preoccupation, a limited endeavor that existed primarily to feed the voracious Hollywood appetite for new movie properties.

Film is still king here and the moguls continue to look down their noses at what are, after all, the relatively paltry grosses of the theater. A blockbuster musical raking in $350,000 a week is petty commerce, when "Return of the Jedi" can reap $41 million its first week out. Nonetheless, the theater has made steady inroads over the past decade. New York aside, L.A. stages may well be the busiest in the nation. Although bustle doesn't necessarily mean quality, in the dead of a suffocating summer, when Washington is limping along theatrically, a visitor to Los Angeles is startled to find the place hopping.

The road company of "Dreamgirls" is heading into its 25th week at the Shubert; a spiffy production of the off-Broadway hit, "Little Shop of Horrors," is playing at near-capacity level in the snug Westwood Playhouse after 17 weeks; "Sister Mary Ignatius Explains It All for You" is holding on after 48 weeks at the L.A. Stage Company; at the huge Ahmanson, Lauren Bacall in "Woman of the Year" has already chalked up 12 weeks, despite downbeat notices. And "The King and I" just took up residence at the Pantages.

With a huge population to draw upon, L.A. can sustain the kind of long runs that are mandatory if a big Broadway show is to survive on the road these days. More to the point, however, is the proliferation of theater by and for L.A.--at the Mark Taper Forum, the city's answer to Arena Stage; at the scrappy Los Angeles Actors' Theatre, which is about to build an $11-million, four-theater complex downtown; and at some 80 Equity Waiver theaters, storefronts and pocket playhouses strewn along the endless L.A. boulevards.

By definition, Equity Waiver theaters are those seating less than 99 spectators. Actors Equity, the actors' union, has long since agreed to forego any jurisdiction over them. Consequently, the individual theater is free to strike its own bargains with performers. That can mean nonunion wages, simple carfare or no wages at all. Still, the actor gets vital exposure and in a city that has almost as many unemployed actors as it does swimming pools, the ruling has resulted in a virtual explosion of home-grown productions. While the quality varies radically, Sylvie Drake of The Los Angeles Times frankly views the Equity Waiver phenomenon as "the major catalyst in L.A. theater in the past decade."

The one Equity Waiver show I saw recently--a revival of William Inge's "A Loss of Roses," with Chad McQueen, son of the late Steve McQueen, in the role that launched Warren Beatty's career--did nothing to rehabilitate the play, a 1959 Broadway flop. Still, there's something to be said for a theatrical climate that permits such all-but-forgotten dramas to resurface.

As it has elsewhere, Tennessee Williams' death has provoked a re-examination of his work and spawned various tributes around town to his genius. The Mark Taper Forum has brought back "Cat on a Hot Tin Roof" in a production directed by Jose Quintero and starring Pat Hingle, as Big Daddy, the cancer-ridden patriarch of the richest 28,000 acres this side of the Valley Nile. Quintero's direction is, alas, without much focus, and a steamy play is permitted to fritter away its raw energies.

Williams always said he was writing about mendacity in a Southern family that is conniving for Big Daddy's sizable inheritance. But the lies the characters tell one another, not to mention themselves, are only part of the fabric that is interwoven with the poisonous silver threads of death. Quintero has presumably tried to give the production scope--he has five black servants hovering on the edges of the action, although, inexplicably, only four of the five "no-neck monsters" are accounted for. But what sense of residual grandeur the production can lay claim to stems mainly from John Lee Beatty's bedroom set, hugged by a gracefully curved veranda and wisteria-draped, floor-to-ceiling shutters.

Film credits carry more weight here than elsewhere, and Kirstie Alley, best known as Lt. Saavik in "Star Trek II," has the role of Maggie, the Cat. She is undeniably sexy in a clinging slip, and her face has a velvety allure. But where is the steely determination to wrest the reluctant Brick into bed and produce an heir to Big Daddy's millions? James Morrison's Brick has none of "the charm of the defeated," just a kind of surly resignation. And Hingle contributes a gummy small-town Big Daddy that, to say the least, comes in way under stature. But mostly, the production is a failure of directorial conviction--conspiratorial and confidential, when it should be bold and scheming.

Currently, the big show--in terms of budget (said to be $4.3 million), if not impact--is the Anthony Newley/Stanley Ralph Ross pre-Broadway musical, "Chaplin," at the Dorothy Chandler Pavilion. Purporting to be a stage biography of the silent film comic, the evening is more in the nature of a glossy TV special. The splashy, if irrelevant production numbers, are strung together by some rudimentary narration that alludes to Chaplin's unpleasant nature and his political difficulties, but settles for standard rags-to-riches platitudes. Newley, who made his name playing scrappy lower-class types ("The Roar of the Greasepaint," "Stop the World"), is cast against all physical evidence as Chaplin, a role he endows primarily with his expanded girth and swollen ego.

Actually, there are three Chaplins, Newley merely representing the eldest version and behaving a little like Scrooge as he wanders back through the peaks and valleys of his life. That doesn't prevent Newley from co-opting all but a handful of the songs in the Willy-Wonka-ish score. He perches on a pile of oversized children's blocks to sing the opening number, "A Little Bit of Powder and Paint"; leads the pratfalling extras through "Funny Man," a not-so-funny romp; returns, standing proud, on a stack of oversized film cans to warble "If Only You Were Here," a plea to his dead father. Arriving in the States, he intones a patriotic tribute to "The American Dream," then later, bitter and rejected, counsels the Statue of Liberty to "Remember Me" as he floats out of New York harbor to exile in Switzerland.

The show reaches truly giddy heights, however, in a second-act production number replete with flags, flaming batons, a chorus line of tap dancers and Newley himself, harnessed to what looks like the wreckage of an old Cadillac, but is merely the apparatus of a "One-Man Band." All of this has something to do with Las Vegas show business, perhaps, but precious little with Chaplin, himself. The subsidiary characters in his life have been relegated to the sidelines, lest Newley be obliged to relinquish the spotlight, although Scott Grimes (the youngest Chaplin), Andrea Marcovicci (Chaplin's assorted wives) and Jim MacGeorge (Stan Laurel) give good accounts of themselves when asked.

From the stage, Newley recently took one of the L.A. critics to task for failing to appreciate the worth of this endeavor. But what there is to appreciate largely boils down to a physical production, lavishly mounted (the basic set is a London music hall, which in turn houses Times Square, Hollywood, Chaplin's film studios, Hearst's castle and some of Switzerland). Michael Smuin, the choreographer who salvaged "Sophisticated Ladies" during its tryout, has managed the transitions from one big number to the next with considerable adroitness, and "Chaplin" has a dreamlike swirl to it that would be effective if there were any show there to begin with. But the fact is that "Chaplin" is marked--indeed, overwhelmed--by Newley's personality from beginning to end, and he's dead wrong for the assignment. Woody Allen might as soon play "Gable."

At the other end of the spectrum is "The Last Tape (and Testament) of Richard M. Nixon," which imagines the former president in late-night exile, pouring his bile and his bluster into a tape recorder. It is the notion of authors Donald Freed and Arnold Stone that pardon without forgiveness is a kind of unending nightmare, and they have written an extended monologue-cum-diatribe, in which Nixon, bearing some psychological kinship with Harold Hughes in his final days, wrestles with his demons, wallows in self-pity, rants, roars and makes a fairly arresting spectacle of himself.

This is not mere Nixon-baiting, however. The authors have a startling thesis to advance by the flickering firelight in Nixon's study: Watergate was actually masterminded by the beleaguered president to prevent a takeover of the country by "the bare-knuckled boys," who preside over the military-industrial complex. Rather than be a puppet bobbing to their ruthless bidding, the play asserts, Nixon engineered his own downfall and got himself eliminated from the nasty game on what may be the greatest foul of all time.

If the play were merely its thesis--Watergate, as an ironic act of heroism--it might have trouble finding too many takers. But there is also the character of Nixon, as the authors imagine it and actor Philip Baker Hall fleshes it out. The portrait that emerges in the claustrophobic 38-seat Half Stage of the Los Angeles Actors' Theatre throbs with a kind of Strindbergian paranoia. Hall works from the inside out. Initially, he seems to bear little physical resemblance to his celebrated subject, but the contradictory emotions actually remold his face. By the end, he has acquired even the celebrated jowls.

In the fall, the play will move off-Broadway-- the Cherry Lane Theatre is currently being mentioned as a berth--under the auspices of film director Robert Altman. One of Altman's provisos is that the piece be trimmed to 95 intermissionless minutes. He should probably also insist on a more phantasmagoric climate than director Robert Harders has managed. Still, it's a surprising piece, and not the least of the surprises is that it turned up in L.A., not Washington, which ought to be more hospitable to this kind of undertaking.

But theater in L.A. is simply not what you expect. Money is hardly the final measure of a city's theatrical pulse. Nonetheless, the third edition of the California Theatre Annual, about to be published, reveals some startling statistics. Totaling reported box-office grosses for the 1982-83 theater season in L.A., the annual came up with $34.6 million. By comparison, San Francisco, commonly thought to be the cultural capital of California, checked in with $16 million.

So much for our misconceptions about the laid-back populace of the City of the Angels, frittering away the hours in the flickering half-light of the silver screen.