Moss Hart blitzed Depression-era Broadway with smash-hit comedies, capturing a 1937 Pulitzer Prize for You Can't Take It With You. In 1941, with Kurt Weill and Ira Gershwin, he created Lady in the Dark, a musical play that presaged the thoroughgoing integration of text, music, and dance which would make Oklahoma! such a landmark in 1943. While directing Lerner and Loewe's My Fair Lady in the mid-1950s, he doctored Lerner's libretto so well that, by the time the show opened in New York, it worked like gangbusters and racked up the longest run of any musical in Broadway history. He wrote such movies as Gentleman's Agreement and the 1954 remake of A Star Is Born. And Act One, Hart's rhapsodic yarn about his collaboration with George S. Kaufman, is probably the most beloved theatrical memoir of the past century, if not of all time.

Hart's personal life was action-packed, too. As one of the smart set's most eligible bachelors, he peacocked around New York and Hollywood, socializing with the members of the Algonquin Round Table and cruising the high seas with Cole and Linda Porter. In middle age, he married Kitty Carlisle, an actress principally famous for being famous. The Harts became a New York power couple, as glamorous and sought-after as the Lunts or the Luces. Hart's death in 1961, at the age of 57, seemed especially premature since he was the father of two small children.

If Hart is overdue for treatment in a comprehensive biography, the wait has been worthwhile. Dazzler: The Life and Times of Moss Hart by Steven Bach (Alfred A. Knopf, 416 pages, $27.50) is a vigorous literary performance that sparkles as brightly as its subject. Bach, former head of production at United Artists, is the author of a 1985 bestseller about the making of the disastrous film Heaven's Gate. After seven years' research and writing, he has produced a biography of Hart which, though conventional in form, is admirably streamlined and paced like a good novel. Bach may not quite have his subject's flair for English usage, but his writing doesn't suffer by comparison. Devotees of Act One will be relieved to discover that Dazzler, with its lively account of backstage life from Abie's Irish Rose to Camelot, is as entertaining and full of heart (no pun intended) as Moss Hart's masterpiece of autobiographical fantasizing.

Hart seems to have harbored theatrical ambitions from the moment he crossed the threshold of a theater. Born into semi-genteel poverty in 1904, he grew up on East 105th Street in Manhattan and East 156th Street in the Bronx. He dropped out of school at 15 to live out the Horatio Alger cliché. First, he pushed a cart around a fur vault, then upgraded to the rag trade, and finally snagged a job as a gofer for a shabby impresario named Gus Pitou.

The Pitou organization, which managed a string of road companies touring undistinguished plays to provincial cities, was the underbelly of show business. But working there gave Hart a toehold in the New Amsterdam Building on West 42nd Street, nerve center of Broadway, where Pitou's fellow tenants included producer Florenz Ziegfeld. The ambitious Moss, already lousy with charm, networked around the building, scoring comps to the latest shows and meeting up-and-comers like Dore Schary, George Cukor, Edward and Joseph Chodorov, and Cary Grant (then known as Archibald Leach).

In his spare time, Hart cobbled together a script that the boss accepted for production. Pitou sent Hart's ramshackle comedy The Beloved Bandit on a pre-Broadway tour but, after two changes of title and a summer hiatus for rewrites, the play died in Dubuque. Undeterred, the fledgling dramatist proceeded to develop his craft by directing amateurs and writing sketches for Jewish community centers, summer camps, and Borscht Belt resorts. In 1930, he came under the tutelage of Kaufman, unsentimental master of wisecracks and one of the most gifted collaborators in the history of the American stage. Kaufman helped Hart transform his rough draft of Once in a Lifetime into a hit and introduced him to an urbane crowd that included the Algonquin wits. As a result, the eighth-grade dropout became a sophisticate, acquiring a legendary appetite for luxury. But reports indicate that, no matter how cultivated in later years, this New Yorker who helped bring Henry Higgins to the musical stage never lost the vocal distinctions of the Bronx.

Hart was almost as well-known for his protracted course of psychoanalysis as for his plays. He first consulted an analyst to alleviate bouts of depression, and stayed in analysis for a period that amounted to half his life. He even wrote a musical, Lady in the Dark, about the dream life of an analysand. While Hart may have made free confession in his psychiatrist's consulting room, he left behind few confidences to aid biographers in penetrating his amiable, sphinx-like façade. Bach captures the convivial aspects of his subject's personality but can merely speculate about the internal tumult that nourished this very private man's serious, less successful plays, such as Christopher Blake and The Climate of Eden.

Bach portrays Hart as a victim of his own success. The playwright wasn't yet 26 when Once in a Lifetime made him the toast of Broadway. Early acclaim ensured that subsequent plays, regardless of their quality or depth, would find willing producers. "This was enviable," writes Bach, "but creatively booby-trapped....[C]ertainty that the show would go on encouraged flippancy and precluded the reflection, refinement, or real bite that might have resulted without that comfortable guarantee of an opening-night curtain." After 1943, the hard-working Hart had numerous successes as director and play doctor, and produced workmanlike scripts for the screen. Yet his inspiration as a dramatist had peaked in the 1930s with You Can't Take It with You and The Man Who Came to Dinner, both written with Kaufman.

As a playwright, Hart was adept at creating characters with camp sensibilities, such as Sheridan Whiteside in The Man Who Came to Dinner and Russell Paxton in Lady in the Dark. In private, he dolled up his wife like a toy from Madame Alexander's in creations by Balenciaga or Schiaparelli. Mrs. Hart, who declined to cooperate with Bach's research, has compared her married years to a "continuous drawing room comedy" and been quoted as saying, "Moss directed my clothes the way he directed a play." Not surprisingly, there were rumors, and Bach isn't the first to gossip in print about the possibility that Hart had romantic entanglements with men. Dazzler has been anticipated as the book that would "out" the playwright definitively, but this turns out to be a matter of probability rather than proof.

In the recent memoir Original Story By, Arthur Laurents remarks: "Rumors are quick about a man who marries late, as Moss did." Laurents points out that "Kitty married late, too, but not a whisper; there rarely is about a woman." Bach pursues the reports doggedly but never catches his subject with trousers down. The closest the biographer comes to verifying the rumors about Hart's pre-marital love life is testimony from an actor-turned-psychiatrist whose objectivity is unsubstantiated: "Moss was consumed with efforts to find his sexuality. He was sexually active but also confused and may have been experimenting. Sexuality per se was less important to him than wanting to love and be loved. He used to say, 'If I could love somebody, I wouldn't care if it was a man, a woman, or a pig.'"

Bach's case for Hart as a gay role model might be more palatable if he strained less forcibly to make it. He loses his sense of proportion when he takes as gospel The Lord Won't Mind, a Stonewall era bodice-ripper (or, more accurately, crotch-unzipper) by Gordon Merrick, who played Richard Stanley in the original production of Hart and Kaufman's The Man Who Came to Dinner. Merrick ostensibly used Hart as the inspiration for a minor character in the novel, a middle-aged stage director of considerable renown; he describes "the swooping hairline, the Mephistophelian features, the elegantly tailored figure." The character, Meyer Rapper, lives in the Waldorf Towers, as Hart did, attended by an efficient butler like Hart's. He's also predatory, proposing sex as quid-pro-quo for casting a much younger man in a Broadway play. "Now Charles," he says to the startled juvenile, "I'm afraid you'll have to learn right from the start what a sordid business the theater is." After a little sparring, Rapper explains: "I'm sorry to make it sound so cold-blooded. But my analyst would never speak to me again if I went into rehearsal with this situation unresolved. I might easily have a breakdown. It wouldn't be fair to my backers."

Merrick's description of Rapper (the voluptuous animation, the dandified togs, the pretentious locutions), along with the array of photographs in Dazzler, suggest what an imposing self-creation the mature Hart must have been. But nothing in Bach's text supports the wholesale identification of Hart with Meyer Rapper or Rapper's modus operandi. On the contrary, in Bach's portrait, Hart is unfailingly generous and decent: faithful son, supportive brother, loyal friend, professional mentor. In an episode often recounted in the New York theater, Hart gave the cast of My Fair Lady a two-day recess so he could coach the tenderfoot Julie Andrews, who was in danger of being replaced in the role of Eliza Dolittle. His acting tutorial saved Andrews' job and gave her a leg up on stardom.

Every chapter of Dazzler confirms Hart as a man unlikely to abuse his power, who lived, as Bach remarks at one point, a "life of uncommon generosity in an often mean-spirited world." Arthur Laurents echoes that judgment in Original Story By: "Moss was a man who managed to be exceptionally kind and still be funny." The heartening message of Dazzler is that the humorous, humane voice of Act One is the real voice of Moss Hart.