Name-calling, gossiping, and cruel competition, she asserts, are not behaviors inherent to girls. Instead, in her latest book, "Girlfighting: Betrayal and Rejection Among Girls," the college professor shows - with help from more than 400 interviews - how this behavior is culturally learned.

From an early age, Ms. Brown says, girls are subjected to strong messages from the media and society in general. They hear that they must conform to certain ideals of femininity, beauty, and romance to be popular and successful - and that in doing so, they shouldn't trust other girls with whom they are in competition.

Mean, aggressive behavior is the natural result, says Brown.

Fifteen-year-old Bahtya summed it up for the author: "Fighting's the popular thing to do. TV, media, newspapers, it's like they teach girls you're supposed to fight. It's a constant competition or race for attention."

But Brown didn't write "Girlfighting," her third book about girls, simply to grouse about the media. She challenges the popular notion that "girls will be girls," gives readers a sense of hope that this trend can be reversed, and suggests practical ways to support girls and bring about social change.

"I was concerned that we as a society were blaming girls for something that we needed to be accountable for," Brown said in a telephone interview. "We have this notion that girls are naturally jealous and nasty, but we didn't think about cultural messages that make girls feel powerless unless they can denigrate other girls."

Engaging with girls in ways that make them feel more confident and powerful on their own, so they are less inclined to put down others, is the goal. Brown devotes a chapter to concrete steps for doing this, including encouraging girls to enter the sports arena and honing their sense of fairness and justice.

At the same time, says Brown, a little feistiness at the right moment isn't such a bad thing.

"We had heightened attention in the '90s about girls' loss of a voice," she says. "Now they are speaking out more, often because they don't want to put up with unfairness or just because they are trying to figure out what it means to be a girl. A lot of positive social change has come about as a result of anger."

Some of Brown's favorite interviews in "Girlfighting" are with girls who can differentiate between constructive feistiness and purely negative squabbling - and recognize how the latter robs them of valuable energy. Eleven-year-old Lily, for example, recognizes the price of divisiveness. "If we could put all our talents together," she told Brown, "we can't, but if we could, we'd like, you know, it'd just be no holding back."

Another girl who particularly impressed Brown is Maritza, an eighth-grader who wrote a telling story about a princess who isn't beautiful and, as a result, has only a peasant as her suitor.

As the princess grows older, Maritza wrote, she learns to be content with her life and less ashamed of her looks, but still feels a nagging jealousy for a beautiful duchess who "had everything she wanted."

Maritza's story, Brown writes, reminds us of the rewards and disappointments girls face in the present culture and how cultural ideals of beauty, romance, and femininity nurture jealousies between women that can choke out possibilities for real social change.

Brown deliberately chose to end each chapter with anecdotes from insightful girls like Lily and Maritza.

"These are the girls who see the world differently," Brown says, "the ones who see the need for girls to work together and not pursue dead ends. We don't hear from them often enough."

Girlfighting: betrayal and rejection among girls
Lyn Mikel Brown
NYU Press259 pp, $27.95