By Margot Peters

Knopf. 641 pp. $29.95

WHEN Broadway's legendary bad-boy-genius, Jed Harris, was making plans to produce the Edna Ferber-George S. Kaufman comedy "The Royal Family," (which he summed up as a "fond spoof of the more legendary aspects of the Barrymores"), he had the script sent to Ethel Barrymore with the gleeful idea that she might want to play herself. Ethel replied with a threat to sue. She did not, however, and "The Royal Family" became a long-running, often-revived hit and a successful film and has been greatly responsible for the public's perception of the Barrymore acting dynasty as a flamboyant family of theatrical egotism and eccentricity. This impression was not amiss, although their fictional counterparts appear to have been far better company and at least were good for a few laughs.

Matriarch of the Barrymore clan was the actress Louisa Drew, Mummum to her three grandchildren, Ethel, Lionel and John. Her third husband, John Drew, a roguish Irish comedian, left her widowed at the age of 41, an indomitable, undemonstrative woman determined that her family should thrive in the theater. She trained her daughter Georgianna for the stage. Georgie became a leading lady and married the mercurial Maurice Barrymore (real name Herbert Blythe), a talented, charming actor, born in India of British parents, fond of drink, uncompromisingly unfaithful and destructively extravagant. Their three children were left in Philadelphia with the dour Louisa as their parents toured, sometimes appearing together or opposite other great actors of the day: Edwin Booth, Lawrence Barrett, Modjeska, Lily Langtry and Mrs. Fisk. To their young daughter and two sons, on their brief visits home they seemed infinitely glamorous.

One would assume that the young Barrymores, bereft of parental attention and maternal warmth, would turn to each other for consolation. However, they did not seem to like each other very much. There were substantial reasons. Lionel was a sober youngster, unable to compete for Mummum's small handouts of occasional affection with the more ebullient Ethel and the devilish John, who, at the age of 4 after a large dinner party given by his grandmother, was found unconscious on the dining-room floor, drunk after having drained all the wine glasses. Perversely, Louisa Drew favored bad little John above her other grandchildren.

When Ethel was 14 and Lionel a year younger they launched their stage careers with Mummum (their mother now dead) in a touring company of "The Rivals." Ethel had found her place, but Lionel hated the theater, and he and John both set their hopes on becoming artists. Two years later, discovered by Charles Frohman, Ethel was on her way to early stardom (her name in lights above the play's title within five years), capturing English and American audiences and numerous ardent admirers, Winston Churchill among them. She had a piquant charm, a youthful beauty and a voice that was memorable. Lionel, after an unsuccessful attempt at painting in Paris, came groaning back into the theater, forced to appear on the stage and to eventual success as a matter of survival. He possessed little charm, a sort of chaffing presence -- but he also had an unforgettable voice.

John, living a bohemian life in New York, had turned into a competent political cartoonist, albeit mainly supported by Ethel. Mummum was dead, and Maurice institutionalized, his brain destroyed by syphilis. John finally gave in to the lure of the greasepaint. When their father died, Lionel was in El Paso with "The Other Girl," Ethel in Philadelphia with "Sunday" and John in Buffalo with "The Dictator." Lionel did not come to the funeral. As always, he was somewhat of an outsider to the family's triumphs and tragedies.

Despite his late start, John soon became the greatest star of the triumvirate, as well as the most admired stage idol of the time (1912-1925) with starring roles in "The Affairs of Anatol," "Peter Ibbetson," "Richard III" and "Hamlet." Offstage he had taken on the flamboyant manner of his father. He was unpredictable. One of his contemporaries described a night with him as like being locked in a closet with all four of the Marx Brothers. He drank heavily, his affairs were always a scandal, his marriages and divorces made headlines. But his profile was magnificent and his voice splendidly timbered.

Lionel was the first Barrymore to appear in films. In 1909 he joined Biograph and starred in numerous D.W. Griffith productions including "The Informer." Ethel and John soon followed him into the movies, but Lionel was to be the most successful in this medium. In 1926 he signed with MGM and, in the 27 years he was under contract to that studio, moved from leading man to gruff old Dr. Gillespie, a character which immortalized him on the screen. A leg injury in the '30s, compounded by severe arthritis, kept him addicted to pain-killers and forced him to play out the remainder of his career in a wheelchair.

The Barrymores made a rare appearance together in the film "Rasputin" with Lionel in the title role, John as Prince Youssoupoff, and Ethel as the czarina. The year was 1933, and the film remains as a marvelous record of the Barrymores' talents. What stands out is their extreme individuality. They were never ensemble players and, once removed from childhood, went their own ways. Ethel, a dedicated Catholic, was never able to forgive John for following their father's profligate path. SOUND in films arrived too late to display John in his full glory. The "great profile" was ravaged, the wonderful voice grown stilted as drink caused him such lapses of memory that he had to read his lines from cue cards. One of the last, great films he made was "A Bill of Divorcement" in 1932, playing the young Katharine Hepburn's shell-shocked father. Hepburn recalled that he asked her to come to his dressing room to run over a scene with him. To her amazement he was wearing a filthy, food-stained, makeup-caked bathrobe, which he tore from his body to stand naked before her.

"She just stood there, looking at me," Barrymore confessed, "and finally I said, 'Well, come on. What're you waiting for? We don't have all day.' She didn't move, so I did and started to grab her, but she backed away and practically plastered herself against the wall. 'By God,' I said, 'What's the matter?' and she said, 'I cahn't.' I said, 'Never mind, I'll show you how.' She started babbling, 'No! No! Please. It's impossible. I cahn't.' I've never been so damn flabbergasted! I said to her, 'Why not?' And what do you think she said? 'My father doesn't want me to have any babies!' and she edged over to the door and made a quick exit."

Lionel was to say: "The public has a trick of setting somebody on a pedestal, just to tear him down again. It's natural -- old as ages. The trick is to keep off the pedestal if it looks too high." But no one, at least in America, wants to tear down the name of Barrymore. We are sadly deficient of dynastic icons. Our theater and film stars have always been our royalty. Margo Peters seems to understand that. She has avoided sensationalism and has rattled few skeletons. If the title The House of Barrymore has a pretentious aura, the writing does not. The book is well researched and documented. Peters, in fact, has collected so much material and apparently felt so compelled to include it all that the participants in what should be a family drama are obscured by it.

Louisa Drew -- Mummum -- is quoted as having said, "Waves and actors are much alike, they come for a little time, rise to separate heights and travel at varying speed and force -- then are gone unremembered." That was before the movies. All three of the Barrymores appear often on late-night television. They are remembered -- but as three quite disparate personalities -- and The House of Barrymore seems unable to unite them.

Anne Edwards's latest book is "Royal Sisters -- Queen Elizabeth and Princess Margaret."