Recalling Hollywood's heyday; L.B.'s daughter, Selznick's wife; A Private View, by Irene Mayer Selznick. New York: Alfred A. Knopf. 385 pp. $16. 95.

At the heroine's Beverly Hills engagement party Marlene Dietrich strolled in fresh from ''The Blue Angel'' and upstaged the bride. Her father (the old lion of Metro-Goldwyn-Mayer) and her fiance (the young lion of Paramount) fought so violently over her marriage that she fainted. For their honeymoon her husband arranged dinner at the White House with President Hoover. When the couple's first child was born, director George Cukor sent over an ermine carriage robe for the princeling. They were the reigning royalty of Hollywood, and Irene Mayer Selznick's new autobiography, ''Private View,'' offers a fascinating glimpse inside the screening room of their lives.

She was the daughter of movie mogul Louis B. Mayer, a founder of M-G-M, and a princess who had the temerity to marry David O. Selznick, heir of a rival Hollywood dynasty. While they were not the Montagues and Capulets, she writes, they were, to a certain degree, star-crossed lovers. ''We had one romance with each other and another with the movies,'' Irene Selznick writes of her marriage to the man who produced ''Gone With the Wind'' and founded Selznick International Pictures.

Her memoir is a big, rich, vivid book about Hollywood in its heyday. It reads like a thriller for anyone interested in the mysteries of that glitter city before the big studios became balkanized and the glamour ebbed. It was a celebrity-sequined life, one in which Charlie Chaplin lived just across the street; she heard her father decide one night to make a star out of an unknown Swedish actress called Garbo; the legendary and tragic producer Irving Thalberg became one of the family; Howard Hughes sent her four dozen roses every Christmas Eve; and the dinner parties looked like the front row at the Academy Awards. There was the night, for instance, when Merle Oberon phoned to say she couldn't make it to dinner that evening because she'd developed a blemish on her face ''that mars my beauty.'' The children's birthday parties were always filmed by a studio cameraman with full equipment.

Mrs. Selznick writes with an insider's specific insights into that life and its high points: like the three-year siege of making ''Gone With the Wind,'' the film David Selznick reluctantly produced, on the insistence of millionaire friend and partner Jock Whitney, who had bought the movie rights. She also shares memories and anecdotes of her friendships with a cast of longtime chums like Ingrid Bergman, Katharine Hepburn, and Cary Grant, as well as her surprising tour of duty under the pseudonym Irene Sells as a caseworker for the Los Angeles County juvenile probation department. Apparently a woman of considerable heart, she is the sort of self-described ''specialist in responsibilities'' whom friends and family turn to for help with the production numbers of their lives.

Mrs. Selznick writes about it all with wit, verve, grace, and nearly total recall. She also describes firsthand, with compassion, the inner workings of the movie business, which sometimes brutalizes those within it. And she writes with cool discretion at a time when steamy, erotic gossip hypes too many Hollywood memoirs.

For all the book's assets, there are a few flaws. It gets off to a slow start with her childhood years in Massachusetts, when her father, Louis B., rose from movie distributor to producer. But when the Mayers arrive in Hollywood, it begins to hit its stride with cameos of early life - like the dewy mornings on horseback, riding out with her father and a group of lawyer or banker friends for breakfast at the Hillcrest Club.

But the real star of the book is David O. Selznick. From the moment he shambles on camera, ''Private View'' becomes riveting. When he exits, the pace flags a bit. Big, awkward, impulsive, generous, idealistic, and idiosyncratic, he roared through life like a tornado through a cornfield. As driven as he was talented, he turned out a string of dazzling successes. In addition to ''Gone With the Wind'' they included ''A Star Is Born,'' ''Dinner at Eight,'' ''David Copperfield.'' His name became synonymous with excellence until ''Duel in the Sun.'' But he failed as a husband and father.

In one of the most poignant chapters in this book Mrs. Selznick writes of the disintegration of their marriage, of his infidelity, and her decision to divorce him after 15 roller-coaster years. With the spunk that was to change the course of her life, she pulled up her tinseled sox and gave a dinner party for 18 the weekend he moved out. Then instead of floating idly on the lily pond of Hollywood society, she abandoned that life. She struck out on her own and moved back to the East Coast to carve out a successful career as a Broadway producer. How successful may be judged by the fact her second production was one of the great coups of the modern theater: producing ''A Streetcar Named Desire,'' which involved such volatile talents as playwright Tennessee Williams, director Elia Kazan, a gifted young mumbler named Marlon Brando, and, in the London production , director Laurence Olivier, with his wife Vivien Leigh as Blanche.

Several other hits followed, including ''A Chalk Garden'' and ''Bell, Book, and Candle,'' until one day she suddenly decided to quit while she was ahead. This book followed, in her leisure years.

Winding up her autobiography, she writes of having had three lives: as daughter, wife, and producer. ''The theater furnished me with a third act. I suppose this book is a review of all three. I'd have settled for so much less.'' The irony is that there could be more, at least on screen: Irene Mayer Selznick's life would make a terrific movie.