Since 1970, Kennedy Fraser has written about fashion for The New Yorker with the intelligence and thoughtfulness that her colleagues bring to music or dance--and a brio that's her own. With less brio, though, in these selections, as the decade advances; and more concern. As she remarks, she took up the assignment ""at the very moment that feminine fashions ceased to count"": mini-skirted women were not about to to drop their hemlines a couple of feet and adopt the midi. The Fraser of the early Seventies does not exult: fashion is real to her--whether the apricot robes of Hare Krishna-ites or the reckless dandyism of Bianca Jagger (a standout piece, on ""Style""); and the triumph of the multitude is, for fashion, the triumph of the customer over the creator, of business over art. What is doomed, moreover, is not only haute couture (brilliantly apotheosized in an essay on Balenciaga) but also such Seventies spillovers as London's Biba: the one department store--Fraser writes in '74--""daring enough to offer us life, spoof, and romance, too."" By '77 it is gone--overrun by the expansion of familiar, no-nonsense Marks & Spencer. ""Back to Reality""? Rather, out to the gym and the jogging-track, to be fit to wear the new unconstructed clothes. Into denim--""under the illusion that denim brings freedom"" (the rich woman in a denim skirt) or, ""for its uniformity and as a purge"" (overalls in Soho). And, into the lookalike clothes of top American designers: genuinely suited to mass production; artificially pricey; sold by label, by promoting the designer as a personality--so that ""purchasers would get the feeling that they were acquiring not things, like sheets or blue jeans, but a little piece of the person whose signature these things bore."" In the absence of old verities and of innovative design: merchandising and hype. Fraser reaches that conclusion via the acid title essay--on the invidiousness of a trend-setting mentality in general. She also reviews the new clowning fashion photographs and the razzmatazz fashion openings. And she ponders the alternatives--the personal ""uniform""--and the special cases: the (ambiguous, ambivalent) executive woman. As for fashion now: ""The only real faux pas . . . is to lack self-confidence."" In tote: the decline of fashion, elegant or exuberant, traced with sensitivity and panache.