ONE painting by Grant Wood is almost as well-known at least in this country--as the "Mona Lisa." "American Gothic" has been plagiarized, adapted, exploited, used as a motif in countless cartoons, home-made Christmas cards and propaganda posters supporting nearly every side of nearly every public issue from women's rights to the nuclear freeze. Its image of an Iowa farm couple standing in front of their home, the man holding a pitchfork and both parties wearing curiously strained, deadpan expressions, has become a part of our folklore as surely as the ride of Paul Revere and the story of Washington and the cherry tree--two other subjects that Wood has treated in memorably ambiguous paintings.

Of those who know the painting and its many imitations, the odds are that not one in 10 would recognize the name of the painter. This is immortality of a sort, but a curious, back-handed sort that reflects the fate of Wood's work as a whole. Until this year, there had been only one museum show devoted to him--a memorial exhibition at the Art Institute of Chicago not long after his death in 1942. Wanda Corn's study, which may help to rehabilitate his reputation and make him better known to the general public, was prepared in connection with the second major Grant Wood exhibit in history--a show now housed at the Whitney Museum in New York and scheduled to visit Minneapolis and Chicago before finishing its tour in San Francisco a year from now. As reflected in the book's 32 color plates and 214 black-and-white illustrations, it is a show of more than passing interest, not only for the quality of the best items on display but also for the story behind the pictures.

In the 1930s, after "American Gothic" had made him famous, if not rich (it sold for only $300), Wood contracted with a publisher to write his autobiography. Entitled Return from Bohemia, it never lived up to its title, petering out and remaining unfinished after a loving treatment of the painter's boyhood on an Iowa farm. Although it leaves much unsaid, this is actually a significant document because the period it discusses is the source of inspiration for all of Wood's most significant work in the last dozen years of his life. The Bohemia from which he "returned" was one that he had visited as little more than a tourist. He made four trips to Europe, but the longest lasted only 14 months and their effect on his techniques and choice of subject was superficial. There are Grant Wood paintings from his earlier years in which he tries to look like Van Gogh or Monet, but clearly his heart wasn't in it. In the 1920s, he became established as a sort of artistic handyman in Cedar Rapids and he used a variety of styles without much distinction for portraits, murals, home decorations and even the design of a massively banal, stained-glass war memorial window. He even ventured into sculpture with found objects--flowers made from junk which he labeled "Lilies of the Alley."

When he found his true style around 1930, it was a return not so much from Bohemia as from aimlessness and lack of focus. Having become reasonably fluent in a variety of styles, he finally worked out one that was distinctively his own, though derived from such diverse sources as the Flemish masters of the Renaissance, American primitives and the 19th-century mass-market art of Currier and Ives. For his subject, he chose not only Iowa but essentially the Iowa of his childhood, not the rapidly modernizing and growing towns of the 1920s and '30s. His rejection of modernity included not only styles but subject-matter; his best mature paintings include no reference to electricity, no machinery more advanced than a horse-drawn wagon or plow. The chief exception reinforces the general rule; it is a 1935 painting called "Death on the Ridge Road," which shows a car and truck about to collide on a country road, with telephone poles looming in the background like crosses in a cemetery.

Otherwise, he is quite explicit about the orientation of his paintings toward the past. In "Arbor Day," a tree is being planted in the yard of a country school with no other trees in sight--a clue that the scene is set in pioneer times when trees were rarities on the prairie. His "Dinner for Threshers," a painting that seems modeled on Leonardo's "Last Supper," he specifies the date as 1892, although the event could have happened almost anytime. There is a mystique in his portrayal of farmers engaged in ageless forms of toil that put them in deep harmony with the earth and its seasons. Wood was not inclined to paint nudes (though one, for a mail-order lithograph series got him banned from the U.S. Mail), but some of his scenes of farm work (notably "Spring Turning") show the rolling hills of the Iowa farm country as the thinly disguised flanks of a giant earth goddess.

Even in Corn's highly readable and lovingly detailed discussion, Grant Wood does not emerge as a major artist. The regionalist movement that he launched in the 1930s petered out even before his death--a victim of America's changing moods and Wood's own lack of adaptability--but remains a distinctive episode in our art history and one that deserves to be known. This modest but expertly prepared study deserves the attention of an art community that has given Wood less than his just desserts.