GIACOMETTI: A Biography. By James Lord. Farrar, Straus and Giroux. 575 pp. $30.

ODDLY ENOUGH, this biography of a Swiss sculptor with an Italian name is a profoundly American book. James Lord, the 63-year-old New Jersey author, is in that long line of sensitive, intelligent, questing Americans who since the inception of this country have gone abroad and returned home with something only they could find. It is true that Alberto Giacometti (1901- 1966) achieved almost worldwide recognition before his death, but for the majority of us it was subsumed in that intimidating card-file of 20th-century avant-garde art that we carry around in the back of our heads.

That is not to say that one could ever truly forget those spooky, emaciated, elongated bronze figures that are Giacometti's permanent stamp on ou visual consciousness. But only that he was one of a big handful of Paris-based, midcentury innovators who sort of blended together when we were out of sight of his hypnotic grotesques. A Giacometti, in other words, was a stylized shape and form that might have materialized out of the totalitarian lower depths, but as for the human being -- it never really entered our minds that there was one.

This is the prize that James Lord has brought back: Alberto Giacometti, in all his dimensions, pathos, anxieties, candor, plus his mad dedication to his work. Nor did this recreation of the real Giacometti just come about as an objective job of work. James Lord, who tells us in the "Acknowledgements" section of his book that the artist "transformed my life," first met Giacometti at a Paris cafe in 1952. He was magnetically drawn to the older man, posed for him, took notes, and became privy to all the disarray of the sculptor's life. (The hovel in which he lived and worked, the never-ending catfight with his unhappy wife Annette, his penchant for whores and the unrewarded loyalty of his brother Diego.) Lord, in spite of his admiration -- in fact, because of it -- spares us no detail of a man he considers to be a genius and therefore beyond the law, so to speak.

The facts about Giacometti's life before it assumed all its mature tics (the never-extinguished nightlight, 40-80 cigarettes per day, potency only in sexual trios) were fairly unrevealing on the surface. His father was a well-known local painter in the Bregaglia Valley of southeastern Switzerland, his mother the usual strong Italian lady who raised four children of which Alberto was the first. Apart from suffering from a case of mumps, which left him sterile in later life, Giacometti seems to have been a quiet, moody boy who was quite over-protected. He both painted and sculpted as a youth, encouraged by his father, and after bumming around Italy absorbing great masterpieces finally went to study sculpture in Paris in 1922.

The timing, of course, couldn't have been better. Cubism had already permanently changed the face of classical art and Dada/Surrealism was now dredging up formerly taboo suject matter. Although Giacometti spent five year sculpting from live models at the fairly conservative Acad,emie de la Grande- Chaumi-hours life in Montparnasse dives and ideological back-rooms that deeply imprinted him with the rebellious spirit of the time. Even in later years, when he had fistfulls of dollars and could buy all the first- class whisky and prostitutes he wanted, he could be seen haunting the now seedy venue of his young manhood. His companion on some of these 3 a.m. nostalgia trips was another isolato who remembered the glory days, Nobel laureate Samuel Beckett.

HEROIC NAMES, by the way, naturally tumble forth in these pages -- before he was finished Giacometti even "put down" such former friends as Pablo Picasso and Jean-Paul Sarte, although unlike Lord I think an element of proud perversity had as much to do with these rejections as integrity. Be that as it may, this glamorous constellation of names (including that of another recluse, Marlene Dietrich) is surely only a small if natural part of Lord's story. What is much more to the point is the loving and detailed way in which the author shows us how Giacometti hammered out his famous style through the most arduous trial and error, from tiny sculptures hardly bigger than a pin to the long-necked, leggy humanoids that we all now recognize as Giacometti's copyright.

Without any cooperation from the sculptor's still-living widow, but with an abundance of recall from younger brother Diego who for 30 years acted as Alberto's aide de camp (preparing the armature for the sculptures, supervising the casting), Lord gets us to live out the artistic struggle along with Giacometti himself. The writing of these lonely, epic battles in the grimy studio is a model of its kind -- patient, exact, even radiant but without a whisper of movie music sweeping up and over. In other words, a legtimate contemporary artist can read it with no embarrassment and a layman can also handle it without an interpreter.

The upshot of all this, the thing that James Lord can perhaps be most pleased with, is that he has written a painstaking, powerful biography (15 years in the making) about a man he obviously loved without letting that love get between Giacometti and the truth. You can almost see the author bracing his spine when he has to dig into the sordid, ignoble aspects of the sculptor's life, which were narrowly compulsive and not easy to justify. If I have any valid complaint it is that Lord so identifies with his subject that he sometimes fails, in my opinion, to demonstrate the evidence of "genius" (an overworked word which he overuses) in Giacometti's everyday personality, writings and not always inspired conversation. On a more a more practical level, he never explicitly tells us what languages Giacometti spoke or wrote in -- only Italian and French, I assume -- but which are apparently the basis for the many smooth English sentences that roll from the sculptor's tongue or pen in the book. A small explanatory note about translation would have taken care of one reader's gnashing frustration.

However, English conversationalist or not, "genius" or merely ferociously single-tracked, original artist, distorted, vulnerable man or great one, Giacometti owes his life in words to the most conscientious kind of American seeker a European visionary could hope to stumble on. This is a very tender book made strong by the rigors of close detail.