Upper-middle-class yearning for working-class warmth and vigor is a no-no theme today. Hey, we're a classless society defined by an ascending scale of dollar signs. All we have is that pesky underclass, an un-category like the undeserving poor of Victorian times.

But back in the 1920s, Isabel Bishop (1902-1988) took that yearning and, over a period of more than 60 years, used it to fuel an extraordinary body of work. On view at the National Museum of Women in the Arts is an excellent selection of this important American artist's drawings and prints accompanied by several key paintings. Her works are by turns charming and monumental, classical and modern, affecting and severe. But they all reveal in greater or lesser degree a powerful longing for unrepressed vitality and a carefully preserved distance from it. It's the tension between the two that gives Bishop's art its edge.

Curated by Linda Weintraub, director of the Edith C. Blum Art Institute of Bard College, the show is as much an index of the artist's available market as a retrospective. Some 77 of the approximately 122 works belong to the Midtown Galleries, the artist's dealer throughout her life. Many of the early drawings on view were discovered by the artist during a sweep of her studio for a Midtown show in the mid-1980s. The plates for two portfolios of early etchings from the 1920s were only discovered after the artist's death and printed posthumously.

In all fairness, however, there is no tired tinge of studio leavings coloring the show. Bishop was a very private artist who worked extremely slowly and never had to depend on her earnings. (At 32, she married a leading neurologist who supported her work.) In view of the superb quality of many of the unsold drawings, one suspects that she kept back things that were particularly meaningful to her. Certainly "Undressing on the Bed," a 1960 nude belonging to Midtown, is one of her finest paintings.

Bishop's personal history would make a wonderful period novel. As much as her art, it belongs to the era of Edith Wharton and Theodore Dreiser. Born to parents of failed intellectual and social ambitions, she was an afterthought, a baby born 13 years after the last of two sets of twins. Her father was a Latin and Greek scholar whose career followed a downward path to less and less prestigious secondary schools. Her mother's lifelong ambition was to translate Dante's "Inferno" into English; the untimely advent of baby Isabel got in the way.

A lonely child, she peeped out of the windows of the family home in a declining neighborhood of Detroit and envied the forbidden games played by slum children in the streets. She must have been strong-willed, though, for at 16 she persuaded a wealthy relative to send her to New York City to study art.

Bishop initially found a mentor in Kenneth Hayes Miller, an artist passionately in love with the great Renaissance masters. At the Art Student's League, he taught her to draw, to find classic forms in modern-day subjects and to work, work, work. Closer to her age was Reginald Marsh, a former Yale BMOC who was earning a living reviewing burlesque shows for the Daily News. His enthusiastic prints and drawings of working-class pleasures were undoubtedly a strong influence.

It took her a long time to find her own voice, though, more than a decade. In 1926 she tried to kill herself at the end of a disastrous love affair, but discovered that "her body just wouldn't die." Around 1930 she took a studio in Union Square, a shabby business neighborhood of New York that provided her with an inexhaustible stream of human subjects.

Finally in 1932, she exorcised her family devils with a major painting, "Virgil and Dante in Union Square." A pencil drawing for the work is in the show. With a Renaissance-like horizontal backdrop of buildings and statuary, a mass of working-class humanity going about their business in the middle-ground, and two romantic hooded figures in the foreground, it forcibly integrates three totally disparate kinds of art in a grand-manner composition. She never tried the experiment again.

From the beginning her draftsmanship had a sturdiness that owed much to her borrowings. She adopted Rembrandt's technique of developing an ink wash into detailed figures by energetic, incisive strokes of the pen. Her method of enlivening chalk portraits with touches of oil and pencil came straight from Rubens. There are echoes of Watteau in her treatment of the way clothes drape over the body and of Degas in her homely treatment of nudes.

But her treatment of her Union Square subjects from the '30s onward is pure Bishop. No other artist has so acutely portrayed the vulnerability of single women, caught, as she put it, between the "double purpose" of looking for husbands and earning a living.

To a certain extent she patronizes them. Their soft, unformed features, fluffy perms, perky hats, and ruffled, ribboned dresses pulled too tight over bulging busts and stomachs are like working-class labels. (In Helen Yglesias's recent book on Bishop, there is a hilarious photograph of the bespectacled, skinny, severely coiffed and dressed artist painting two plump, permed and made-up Union Square working girls.)

But in a deeper sense, she saw their working lives in downtown New York as the stuff of epic and odyssey. Like Dreiser's Sister Carrie, Bishop's subjects brave the economic and biological necessities that drive them, finding love wherever they can. Some of her best works portray two women, chatting, eating together, waiting for dates. Perhaps drawing on her family experience of the intimacy of twins, she is brilliant at making two figures form a single unit in space, at endowing them with a reciprocal warmth that unconsciously excludes outsiders.

The literary flavor that clings to the Union Square drawings, prints and paintings disappears in her nudes from the '40s, '50s and early '60s. Willem de Kooning is reported to have said, "That woman's nudes are the best damn nudes ever," and he was very nearly right. Bishop's Union Square paintings are often flawed by her uncertainty about background space. The gestures of her pudgy nudes energize the entire canvas. Clipping toenails, dressing and undressing, inspecting corns, these women in unheroic postures have an uncanny monumentality. Drawn in swift ink wash and line or painted in pale pulsating oil washes, they exude a vitality that seems to have overcome Bishop's customary psychic distance.

With its old-fashioned humanism and class-drawn characters, the Bishop show ought to feel dated. Certainly Reginald Marsh prints show their age. But her classical draftsmanship and personal passion for her subjects conspire instead to make her work look better and better as time passes. On view through Sept. 23, this is an exhibition that will grow on you.

Also on view at the museum is "Chansonetta," an exhibition of the photographs of Chansonetta Stanley Emmons (1858-1937). Discovered by Berenice Abbott, this amateur photographer recorded the people and pursuits of rural Maine with skill and an almost encyclopedic attention to detail. The fascination of these images lies as much in the rich paraphernalia of rural life as it does in the spare, seamed features of her subjects. She is no Atget. But there is solid satisfaction in the completeness of her pictorial record.