Boston Brahmin Lilla Cabot Perry (1848-1933) was 38, the mother of three and an accomplished poet by the time she began studying painting seriously, first in Boston, then in Paris and Giverny, the Normandy town Monet transformed into an impressionist mecca.

Perry's late-blooming journey through art and life is now the subject of a first retrospective at the National Museum of Women in the Arts. It is a pleasant but infuriating show.

Clogged with raw data in the form of 75 portraits and landscapes, it makes only one positive point about Perry's art: that she could make very fine portraits, especially of her own daughters. Beyond that, however, it makes a better case for her limitations than for her strengths by exercising no critical judgment whatever in the choice of works, among them far too many examples that are mediocre or worse.

By defaulting on its responsibility to make a case for Perry's art, or at least come to some new conclusions about it, this show merely serves to underscore a longstanding cliche: that Perry's chief claim to fame was that she may have been Monet's closest American friend. That is surely not the sort of information one would expect to find explored in such detail, and at such expense, at a museum ostensibly founded to give women their due.

In fact, the most vivid work in this show is not a painting at all, but a very good half-hour film by the show's freelance curator, filmmaker Meredith Martindale. The subject is Monet at Giverny, as remembered by -- you guessed it -- Lilla Cabot Perry, who wrote about Monet after his death. The narrative, all Perry's words, is spoken by Claire Bloom.

The show itself begins with a tiny, tentative painting of a rosy-cheeked child -- Perry's first daughter, Margaret -- made when Perry was 29 and untutored, revealing an innate interest in the medium. Family portraits of ever-increasing accomplishment follow, the fruits of Perry's first serious studies, undertaken in Boston in 1884, and thereafter pursued with great passion during her first trip abroad just three years later.

With her writer-critic Brahmin husband and three young daughters close at hand, Perry studied in Munich and in Paris during this first European stay in 1887, copying old masters at the Louvre, and drawing from the figure. By age 41, two of her paintings were accepted into a Paris salon, including the portrait of her husband, Thomas Sergeant Perry, one of the first pictures in this chronologically arranged show. A fine rendition of a seemingly strait-laced, bookish professor in a velvet smoking jacket, it is also very brown, the prevailing hue of many Boston academic portraits of that time.

Two years later, after seeing a Monet exhibition in Paris, and pursuing the great man's acquaintance at Giverny (where she booked rooms and returned for nine summers), Perry produced her earliest masterpiece: a full-length portrait of her youngest daughter, Alice, in a blue dress and shiny brown tresses, seemingly about to go before an audience to play her violin. Perry's exposure to impressionism has not yet brightened her palette, but it has surely influenced the highly impressionistic treatment of the background.

In the second section of the show, titled "Giverny and Paris, 1894-97," Perry, during her first extended stay as Monet's friend and neighbor, is deeply engaged in experimenting with Monet's mode of impressionism, in which color was everything, line and form only secondary. Except in a few landscapes, it is clear that Perry couldn't make impressionism work, especially in the figure paintings, and the results are awkward and superficial.

As she soon discovered, impressionism and portraiture simply didn't mix, and though she kept the brighter colors and looser brushstrokes of impressionism, the portraits that followed were forever more attuned to John Singer Sargent than to Monet.

And often with very fine results: Nearly all the great Perrys in this show are portraits, the best of them tracing the growth of the obviously much-beloved Alice, whom we see grow from budding violinist to "Young Bicyclist," an 1894-95 masterpiece, to the beautiful young bride in a lavender gown, painted when Alice was about 20.

The worst Perrys, however, are equally numerous, filling a room devoted to her three years spent in Japan, where Perry's husband was invited to teach at the turn of the century. Clearly influenced by both impressionism and Japanese prints, these garish paintings beg compari son with the work of Mary Cassatt, her close contemporary, whose glorious prints and paintings were also created under the spell of Japanese art. Perry, however, was no Cassatt, and her Japanese efforts are almost embarrassing in the way they circumscribe the limits of Perry's pictorial imagination.

After 1901, when they returned to Boston from Tokyo, the Perrys continued to travel to Paris and Giverny each summer, but also became more involved in the American art world, especially that of Boston, where their Marlborough Street home became a meeting place for the city's intelligentsia, including brother-in-law John La Farge and Bernard Berenson.

Although she became ill with diphtheria in 1923, Perry remained active, thereafter spending most of her time at the family farm in Hancock, N.H., where she made some of her most endearing, most deeply felt landscapes, foremost among them the silvery, Whistlerian "Mist on the Mountain," which hangs in the show's final gallery. How much Perry loved that farmhouse can be seen in tender paintings showing it under a harvest moon, or on Christmas Day in 1926, as smoke curled from the chimney and frozen laundry flapped on the line. These paintings have nothing to do with impressionism, but they bring the artist herself most fully to life. Why this show is subtitled "An American Impressionist" makes little sense.

After surviving her husband by five years, Perry died in 1933 at age 85, and was given a memorial show at the Boston Art Club. There have been small shows since, but never anything on the scale of the current effort at the National Museum of Women in the Arts.

With all its faults, this show does offer the sense of a full, rich life spent making art in very good places. Until a more focused show comes along, that will have to suffice.

"Lilla Cabot Perry: An American Impressionist," underwritten by AT&T, will continue through Jan. 6.