"Who's this thing by -- Ally McBeal?" asked the cabby, dropping off a group of men in front of the John Jay College Theater in midtown Manhattan. There were regiments of women flooding in to see "Patience and Sarah," presented by the Lincoln Center Festival.

"No," he was told, "it's an opera by Paula Kimper."

"An opera by a lady?" the cabby said. "Women! You can't get away from them your whole life, and now they're taking over opera!"

Taking over is putting it strongly, but the last quarter century has seen the emergence of female composers as serious professionals. Judith Weir has blossomed in the 90's with "Blond Eckbert" (just recorded), "A Night at the Chinese Opera" and "The Vanishing Bridegroom," and composers like Sofia Gubaidulina and Kaija Saariaho have made international reputations.

This trend is even more remarkable in pop, in which women play solo or front bands and hence enjoy a greater autonomy than a classical composer dependent upon a symphony orchestra.

Lilith Fair, a tour organized by the Canadian singer-songwriter Sarah McLaughlan and run totally by and for women, has been unexpectedly popular the last two summers.

Ms. Kimper's work, words by Wende Persons, was an event of sorts. The two title characters are women who fall unabashedly and sexually in love.

After the first act, young gay women were roaming the lobby shrilling in falsetto, making fun of opera voices; they're more at home with Melissa Etheridge or perhaps Queen Latifah. "Oh, Zena, I love you!" intoned one clasping a program to her chest as if shot by an arrow.

"Worry not, Gabrielle," warbled her companion, who, though probably 18, had an impressive dramatic soprano, "Zena's here, never fear, I'll get that arrow out of you, dear!"

Eyeing them, several of the men present seemed uncomfortable. "Feels a little like the Bacchae," said one.

Yet at the end of the third act, there was a soaring affirmation in this music of the transcendent beauty of life and love, regardless of sexuality or gender. Members of the audience -- men and women -- jumped to their feet and screamed. That's not impressive merely because a woman composed it; that's just good opera.

There was an Eve of opera -- though for a long time her contribution was erased from the history books. In the 1630's, the earliest days of the form, the beauteous Barbara Strozzi sang her own arias to the delight of the Venetian Academy. Singing as a way of surviving for female composers still holds true, right up to Ani DiFranco and Lisa Loeb.

Signora Strozzi was an heiress, the adopted daughter of the influential librettist Giulio Strozzi. She studied with the great composer Francesco Cavalli (who worshiped her). Her wonderful and often daring settings of texts from operas demonstrate a big talent, far beyond the short dance forms favored by her male colleagues.

The vicious satires published about her effectively caused her to rein in her large-scale ambitions.

Opera and the bigger forms of "serious music" require both practical experience and real opportunity to learn (and earn) from performance, as Ellen Taaffe Zwilich, the Pulitzer Prize-winning composer of large-scale instrumental works, points out.

It has been easier for women to compose pop. But successful women are often more readily co-opted by commercial forces than men are. There are sad, even tragic stories about significant figures like Laura Nyro and Joni Mitchell who for all their success had to fight the record industry to stay viable.

With all respect to the estimable Ned Rorem and the magnificent Francis Poulenc, it could be argued Mitchell is one of the great song composers of the 20th century, more impressive for writing her own words. Like Franz Schubert's, her music erupts from a deeply felt, idiosyncratic emotional life, outside the mainstream. Schubert was probably a homosexual. Both his great song cycles, "Winterreise" and "Die Schöene Müllerin," and the majority of his songs to poems by others deal with blighted love.

Ms. Mitchell, a fiercely independent woman long before the Baptists felt it necessary to remind us that women are subject to men, has also fought battles over validation.

Schubert deliberately plays with conventional forms and accompaniments (like the Alberti bass) only to shock the ear with unprepared changes and shifts.

Ms. Mitchell, with a finely judged irony, uses the conventions of blues, rock and folk to add bite and surprise to her songs. She's not as daring as Schubert harmonically, but has fought to achieve liberation not just from men but from the inhibiting chord progressions of most successful pop.

Nyro, who died in near-obscurity last year, had her personal problems, but they were surely exacerbated by having to contend with a music business unsympathetic to women's concerns.

Female rappers and rockers of all kinds still come up against old-fashioned male power brokers.

It will be interesting to see if the fantastically talented Paula Cole is co-opted by the corporate world now that one of her songs has become the theme song for the hugely popular television series "Dawson's Creek."

The marketplace can be just as stern a censor of artistic ambitions as the church or an absolutist state once was, and if a composer has to contend with the prejudices of a male-dominated musical world, as well, so much the worse for her. The enormously gifted Tracy Chapman refused to depart from her thorny political muse and has had to struggle to keep from being marginalized.

Still, where a singer can sing her own songs on a permanent document like an LP or a CD, there is always hope. No musician reading the scores for Laura Nyro's songs would realize just from the notes how original and magical a cantata like "New York Tendaberry" is.

Classical composers must trust conductors (still overwhelmingly male) to make sense of marks on a page. "We have to be able to manipulate symbols in various languages, number systems and keys," Ms. Zwilich says. "There are three different systems of tuning in every symphony orchestra."

For many years it was seriously argued that women lacked the cranial resources to compose "serious" music. Studies in left brain and right brain differences appeared to suggest that men were "naturally" more adept at mathematical thinking -- crucial in larger musical forms, just as in the sciences, while women were better at verbal, immediately emotional expression.

Ms. Zwilich just laughs at such notions.

"In fact," she says, "anyone of either sex soon finds out the male numbers theories of composition are all very simple-minded when compared to the real thing."

Such male theorists and teachers were evidently ignorant of the larger-scale works by the genius Lili Boulanger, younger sister of the famous pedagogue Nadia (who nurtured generations of American male composers including Aaron Copland).

Lili was only 24 when she died in 1918, after an agonizing battle with Crohn's disease.

In the immense "Du Fond de l'Abime," her taut logic is overwhelming.

Curiously, in many primitive cultures it is women who are in charge of music, particularly that of lament. Anthropologists like Constantina-Nadia Seremetakis and Gail Holst-Warhaft have studied the ways women create, sing and pass on the songs and poetry of lament as men stand around uncomfortably and watch. Interestingly, the original version of the Gospel of Mark, thought by most scholars to be the first one written, ends not with Resurrection but with women lamenting.

Western music has its origins in what is called the Visitatio sepulchri -- sung dialogues concerning the three Marys visiting the tomb of Christ.

But Mark was redacted to emphasize the physical Resurrection to bring it into line with later Gospels. Women were crucial in spreading Christianity, but the misogynistic rantings of the early church "fathers" eventually robbed them of any leading role in the church. Once Christianity became a state religion, the suppression of women was enforced by law. Since secular Western music evolved from church practice, women were relegated to limited participation in all aspects of society. To be sure, there were exceptions like the 12th-century abbess Hildegard von Bingen, who celebrated the ecstatic union with Christ.

The baby boomers have changed all this. "Classical" composers were freed by the multimedia artist Laurie Anderson, a remarkable and individual voice, a composer in a different sense than the term had been understood before, a performer and conceptualizer unafraid of the most alien terrain. Her influence, direct and indirect, can be felt in the work of remarkable experimentalists like Pauline Oliveros and Eve Beglarian, even in techno pop and the trance music from raves.

Female composers have learned a lesson from men: charity begins at home. Lilith Fair will play 57 North American dates through Aug. 31.

Listeners can encounter the vast range of women creating in all styles from Paula Cole and Emmylou Harris to Dead Girls and Other Stories to Erykah Badu. The concerts are dizzyingly jubilant, insanely inventive and transporting, just what most classical concerts are not.

Ms. Zwilich, composer in residence at Carnegie Hall, underwrites a prize given by the International Association for Women Composers for a female composer under the age of 21. Next season, the New York Philharmonic will devote a week to the Russian composer Sofia Gubaidulina.

Ms. Zwilich, a much-admired mentor of composers of both sexes, is careful to insist that the problems of getting heard and making a living afflict everyone who tries to compose, and always have. She's aware that it's easier for women today than in the time of the gifted Mrs. H.H.A. Beech or the eccentric Ethel Smyth. Nonetheless, she remains cautious: "After a battle, a treaty usually gets signed, so maybe there's peace for a time. That doesn't mean the war is over!"