Once a week, the middle-schoolers at the private Atlanta Girls School go to a unique homeroom session where chatter trumps study.

The get-together is Girl Talk, part of a nonprofit movement where teens besieged daily by the trappings of consumer culture, high-tech gossip gizmos, and "mean girl" mentalities talk to older girls about how to get beyond what seems to them to be a life-and-death drama buzzing around them.

"We mainly talk about cliques and how to deal with mean people," says Jessica Johnson, who joined the Girl Talk program as a middle-schooler and is now one of the leaders at the school. "It's so much better that we talk to them because we're people they can relate to, and they say, 'Oh, you're not centuries older than me; you understand cyberbullying and Facebook.' "

The chat session at the school is one incarnation of a national peer-to-peer mentoring program led by a 23-year-old from Atlanta, Haley Kilpatrick. She has turned a high school revelation and $13,000 of her own cash into a groundbreaking nonprofit group that now reaches 34,000 girls in 43 states and four countries.

The program aims to foster leadership qualities among high school girls at the same time they wield a positive influence on younger, middle school girls.

News reports of the sometimes tragic outcomes of cyberbullying have reinforced the need for answers. Some girls (and boys) live a lonely and unhappy existence in middle school, between the safety of childhood and the freedom of adulthood.

That dynamic became all too clear to Ms. Kilpatrick at age 15, when she was teased and bullied after moving from a public school to the tony Deerfield-Windsor School in Albany, Ga. She started Girl Talk at Deerfield-Windsor in 2002 after watching her younger sister go through many of the same vexations she had faced.

"For middle school girls, everything is an immediate crisis," Kilpatrick says. "So my thought was, if we could help these girls find a meaning and a purpose in middle school, then maybe they wouldn't make bad choices later on."

Since then, Girl Talk has become one of the fastest-growing nonprofits in the country. Girl Talk has received coverage in CosmoGIRL!, Glamour, and Self magazines, and Kilpatrick has appeared on national morning TV shows.

In 2007, Kilpatrick channeled her sense of mission – and, her friends say, her prodigious multitasking skills – into making Girl Talk a full-time nonprofit effort.

Along the way, she turned down corporate sponsorships from clothing and cosmetic firms. If Girl Talk had accepted the sponsorships, she says, "I realized that we'd be sending a mixed message, as we're talking about body image to these girls."

Her stick-to-your-guns strategy paid off. Shortly after that, Atlanta investment fund manager Ron Bell met with Kilpatrick and put an envelope on the table: It had a donation check for $50,000, enough to kick-start a major expansion of Girl Talk.

Named in 2010 as one of Atlanta's "Power 30 Under 30," Kilpatrick – with her straight blond hair and high boots – looks every bit a prep school alumna.

But that image is deceiving, her friends say. She still spends enough time with girls to throw around teen phrases like "I love your guts" that befuddle fellow adults.

"Haley was born to help others, and she devotes her entire life to helping others, not for the credit, not for money, clearly, but because it is all that is acceptable to her," says Kara Friedman, a middle school adviser at Holy Innocents Episcopal School in north Atlanta.

Girl Talk succeeds, Kilpatrick says, by giving younger girls a chance to hang out with their idols a few grades ahead of them. And because it's free. Curriculum, promotion, and salary costs come to about $4 per girl, money raised by Kilpatrick and a small team of co-workers.

Girl Talk provides a curriculum of 100 lesson plans, but it is its approach – talking about a relevant topic each week while imposing a strict no-names, no-mean-talk policy – that tripled the size of the program at Holy Innocents, where about a third of the girls participate, Ms. Friedman says.

Research shows that mentors, even those who are just a few years older, can have a powerful impact on girls. Teenagers who have active mentors in their lives, for example, are 46 percent less likely to use drugs and 52 percent less likely to skip school, according to one recent study.

"[A]t this age peers become so much more important than parents, and I think that's probably why [Girl Talk] is successful," says Pat Wolfe, an expert on adolescent brain development in Napa, Calif.

"When you're moving from middle school to high school, you're going into a situation where you're not sure what the rules are: You're not sure whether you'll have friends, or if you look OK, or if you'll fit in," Ms. Wolfe says. "Anything you can do to help the girls feel less threatened" benefits them, she says.

That includes talking face to face, not just phone texting.

It's all about "shaping these young women into being the leaders of tomorrow, and being the women who will ultimately change the world," Kilpatrick says.

* For more stories about people making a difference, go here.