BY CONTRAST WITH Maureen Howard's four previous novels, Expensive Habits is long and, in the conventional sense, ambitious: the other books are delicate miniatures, elegantly crafted and somewhat elliptical in narrative method, but Expensive Habits attempts to paint a relatively large canvas and does so in a rather straightforward manner. The novel appears -- the impression is fortified by the attendant publicity campaign -- to be Howard's attempt to reach for a larger readership than she has thus far enjoyed; it is an honorable effort, and in no way does Howard compromise her exceptionally high standards in the process, but Expensive Habits is an odd book that is more likely to provoke curiosity and respect than affection and admiration.

Readers familiar with Howard's earlier fiction and her fine autobiography, Facts of Life, will find much here that is agreeably familiar. She writes equally well about two strikingly different milieus, both of which are present in Expensive Habits: the domestic life of genteel but threadbare Roman Catholic families, and the bitchy, narcissistic world of the New York illuminati. Her prose has a distinct and refreshing individuality; she moves with ease between high and low styles, changing gears so smoothly that the reader rarely feels she is calling attention to herself. The sense of irony that permeates all of her work is uncommonly acute, yet it becomes merely judgmental; she recognizes all the weaknesses and self-indulgences of the people she describes and the fashionable ideas they embrace, but her satire is tempered by sympathy, even when silliness is endemic.

There is a good deal of silliness in Expensive Habits, much of it committed by the central character, Margaret Flood. She is a 46-year-old writer who has just been told that she suffers from a heart condition that will kill her in a matter of months: "A mechanical malfunction of the body, the doctors with their machines, Providence, if you will, has taken over. What a swindle -- she has paid her dues, but that's not it. At last she comes to the hard little core of her misery, small and painful as a pebble in the shoe: for years that now seem always, she has controlled the plot." Even now, she cannot resist trying, and indeed it seems she may succeed; she drags herself from New York down to Baltimore, undergoes bypass surgery, and emerges from it with an opportunity to live a new life.

But the brush with "death's bright angel" has had a traumatic effect on this difficult, demanding, temperamental, arrogant woman: it has forced her to examine her past and its many errors, to attempt a rewriting of that past. Before leaving for the hospital "she had worked with a frenzy to set the record straight, as though she were ripping out the seams of her life." After the surgery she does not abandon this effort but continues it with new determination, possessed as she is by the conviction that her books, which are the story of her life, have told that story wrong -- that they are riddled with self-serving falsehoods that have damaged others.

Chief among these, she believes, is her first husband, Jack Flood, whom she married while he was in medical training; they divorced following her discovery that he was having an affair with a nurse. This became the subject of her first novel, in which she portrayed him as altering the results of his medical research in order to obtain an NIH grant; all of these years she has known that "I contracted with myself to write a revenge tragedy, to make an unsupportable thesis of my marriage to Jack Flood." Now it is to him, a distinguished surgeon, that she turns not merely for medical help, but also for forgiveness for "bitter words and fancies, my only consolation, having lost the game."

It is one of many she has lost, thinking she has won: thinking that by reordering life, by faking it in fiction, she can recoup her losses and heal her wounds. But then she is made victim of an irreplaceable loss, one that shakes her house of fiction down to its foundation, and she confronts life's inescapable truth: "For twenty years she has ordered the world, made it accessible, trimmed and fit her stories. More recently, under the trumped-up threat of extinction, she has revised, confessed, approached -- well, her version of the truth. . . . Now she counts herself defenseless, the victim of others' stories -- inaccurate, vicious, consoling. Motives beside the point. . . . Mute, diminished, she is no one in the vast audience. Squinting, on the wrong side of the arena she cannot pick herself out, she cannot heckle."

THIS DISCOVERY of her mere humanity is arrived at by more routes than those provided by Jack Flood and a terrible personal calamity. Others with whom she must contend include her present husband, Pinkham Strong, a spineless patrician from whom she is separated; their son, Bayard, a 16-year-old of exceptional character and maturity; her first editor, Philo Pierce, a cynical fellow traveler in literary and political circles; Sol Negaly, a Hollywood producer with whom she once made a movie -- it sounds for all the world like Nashville -- that "so easily reviled our country and patronized the lower, lower-middle, middle classes"; a Hispanic maid, named (with an excess of irony) Lourdes, whose idle chatter has dreadful consequences; and a small band of ancient radicals -- "grand men and women -- flawed, perhaps fallen, but gods in their day" -- about whom she is attempting to write a book.

It is, on the whole, a larger cast of characters (and the themes they bring along as baggage) than the novel can comfortably contain. Although it is clear what Howard means to do with each particular person, these schemes don't always seem necessary to the central concerns of the book; even when their connection to the major themes -- fate, history, nostalgia, illusion -- is clear, their presence can seem gratuitous. Pinkham Strong rummaging around in the history books, the old women conjuring up memories of their glorious past -- Howard can't let sleeping themes lie, but pokes away at them with a didacticism that is most uncharacteristic. Neither does it help matters that Margaret Flood is never really brought to life, never really takes control of her own story; we are meant to feel a sympathy for her that she never manages to earn.

But if Expensive Habits is a disappointment, it is principally so by comparison with Howard's earlier work: those terse, elusive books that are so much larger than the sum of their parts. By comparison with most contemporary American fiction, on the other hand, it is a serious and accomplished piece of work. Here as in her other work Howard writes about the fads and fashions of the day, about a society eager to cash in on any passing joy or sorrow, but she is having none of that herself; she stands apart, observing "the dumb glory of it all" with an eye that is sharp but kind. If Expensive Habits is not the major work her publisher believes it to be, it is certainly a book rich in integrity and elegance, by a writer who matters.