Psst, Serena is a slut. Pass it on.

Photo: Hubie Frowein

As anyone who has met one—or, worse, been one—knows, a teenage girl is the most terrifying creature on earth. At once deeply sensitive and absurdly jaded, she is the world’s most perfect bullshit detector, a Geiger counter for hypocrisy. Equipped only with her own charisma and wicked tongue, an adolescent girl at the height of her powers is more dangerous than “Page Six,” more undercutting than Gawker, and twice as mean as Drudge. Double that estimate if she’s a rich girl.

Cecily von Ziegesar was just such a teenager. If she wasn’t precisely Paris Hilton, Von Ziegesar was an unusually astute observer among her glittering set, mapping out the invisible hierarchies and jealous undertows within her female friendships. A budding equestrienne, Von Ziegesar was too busy to party much herself: She’d wake up at 6 A.M. to commute by train from Connecticut—where her parents’ relationship was falling apart—to Grand Central, then catch a cab to the institution she considered her refuge on the Upper East Side, the elite private school Nightingale-Bamford. There she learned, at least vicariously, how to negotiate city life from that exceedingly privileged demographic: kids with money, a sense of entitlement, and all of Manhattan in which to exercise it.

It’s little wonder that Von Ziegesar grew up to be a bard of teenage nastiness, documenting it all in a series called Gossip Girl. Perhaps you’ve heard of it—or possibly not. Unlike other young-adult literary blockbusters like Harry Potter, or Hollywood productions like The O.C. and Mean Girls, Gossip Girl has exerted little PR pull, providing Von Ziegesar herself with the neat distinction of being at once an immensely famous author and a complete unknown. With little marketing, her books have sold 1.6 million copies, and the last edition (Gossip Girl No. 7: Nobody Does It Better) debuted at No. 1 on the New York Times’ children’s best-seller list on May 8. There’s a movie in the works. A spinoff launches in November. Yet unlike J. K. Rowling, Von Ziegesar has no personal Website, and her photo appears nowhere on the books’ covers. Still, if her profile is low, teenage girls across the country are her acolytes, finding within Gossip Girl’s pages a stirring fantasy of freedom and an equally stirring fantasy of conspicuous consumption.

“Welcome to New York’s Upper East Side,” begins the first book’s first entry. “Where my friends and I live and go to work and play and sleep, sometimes with each other. We all live in huge apartments with our own bedrooms and bathrooms and phone lines. We have unlimited access to money and booze and whatever else we want, and our parents are rarely home, so we have tons of privacy. We’re smart, we’ve inherited classic good looks, we wear fantastic clothes, and we know how to party. Our shit still stinks, but you can’t smell it because the bathroom is sprayed hourly by the maid with a refreshing scent made exclusively for us by French perfumers.”

Crass, yes. And like other girlie series—Sex and the City is its closest analogue—Gossip Girl would be easy to dismiss as brittle junk. But beneath its stylized surfaces the series is surprisingly sophisticated. Von Ziegesar takes seriously the inner lives of characters who in any other teen narrative would be stock villains, like a judgmental queen bee and her cheating boyfriend. Most notably, the books have a been-there-done-that honesty about Manhattan social mores, and a (take your pick) refreshing or alarming lack of moralism about teen sex and drugs. In Von Ziegesar’s universe, kids have sex without pregnancy scares; they get high in the Sheep Meadow and still make decent grades. Anti-heroine Blair’s bulimia is more of an icky weakness than a full-fledged pathology. At worst, Von Ziegesar’s characters end up embarrassed on the Internet or during an Ivy League interview.

“I always resented books that tried to teach a lesson, where the characters are too good: They don’t swear, they tell their mothers everything,” explains Von Ziegesar, herself a mother of two. “I mean, of course I want to be the responsible mother who says, ‘Oh, there are terrible repercussions if you have sex, do drugs, and have an eating disorder!’ But the truth is, my friends and I dabbled in all of those things. And we all went to good colleges and grew up fine. And that’s the honest thing to say.”

Young-adult literature has always had a split personality. On the front shelf are books that adults hope girls will read: dramas with spunky heroines and melodramas with a moral. But push open the secret compartment, and you find the books girls read on the sly (even girls who don’t usually read): Forever Amber and Judy Blume’s Forever (especially the “Ralph” scene). Back in high school, Von Ziegesar herself read Austen and Tolstoy by day, but under the covers, the 15-year-old Cecily favored V. C. Andrews’s gothic Flowers in the Attic, featuring brother-sister incest and doughnuts poisoned with arsenic. “They were so bizarre and twisted and sick,” she marvels. “I read them all more than once. My mother was like, ‘Why do you buy those books?’ I don’t think she really wanted to know.”

Cecily von Ziegesar in Central Park, surrounded by some of her teenage fans.Photo: Gillian Laub

Gossip Girl operates on just that borderline between irresistible trash and the smarter stuff, so perhaps it makes sense that it arose out of a marketing brainstorm. At the time, Von Ziegesar—who had dropped out of the creative-writing program at the University of Arizona—was working as an assistant editor at 17th Street Productions (later called Alloy Entertainment), a synergistic packaging concern aimed at “concepting” properties for teenage girls. Her colleagues included Ann Brashares, now the author of Alloy’s popular Sisterhood of the Traveling Pants series. And the company had a long history with teen lit: It originated as a distributor for Sweet Valley High, the brainchild of Francine Pascal—who never wrote a single Sweet Valley book, but plotted them all in out-loud brainstorms.

Sweet Valley ruled the teen literary roost throughout the eighties, delighting a generation with the adventures of identical twins Elizabeth (good) and Jessica (evil). The Sweet Valley stories were packed with exciting events—overdoses! kidnappings!—yet despite their excesses, they were resolutely moral, with bad girl Jessica endlessly punished for her naughty ways. Sales nosedived in the mid-nineties, when a new culture rose up with a thousand alternatives to reading—from video games to MTV, the Internet, reality television, and that hydra of adolescent programming, the WB.

In response to this dim market, the company repositioned itself to meet the new business model head on. During a meeting, someone suggested they exploit the newly powerful Internet by launching an anonymous “Web mistress”—call her Gossip Girl. Leslie Morgenstein, the president of Alloy Entertainment, sheepishly acknowledges that the original idea was not for a book per se but a viral marketing hoax: Alloy would concoct a Website, seemingly written by a teen Hedda Hopper, and once the site got “buzz,” launch projects by that invented author. The plan was quickly abandoned. “It was too complicated, and too easy to get caught,” Morgenstein says. Instead, the company presented its book proposal in e-mail, at a time when few publishers checked their in-boxes. It got only one bite, but it was a hard one: Cindy Eagan, now executive editor at Little, Brown. “It was the first e-mail submission I’d ever heard of,” she says. “And I was intrigued by the name. Who doesn’t love gossip?”

At a meeting with 17th Street, Eagan asked who had written the proposal. Von Ziegesar raised her hand. “Cecily took the assignment and knocked it out of the park,” says Morgenstein.

At the time, the project had no plot or specific milieu. Von Ziegesar decided to set it in the world she knew best, the Constance Billard School (a ringer for Nightingale-Bamford), and she created an ensemble of distinctive New York types: the effortlessly lucky blonde, Serena; her envious brunette “frenemy,” Blair; and a cohort of preppy stoner boys, sardonic Williamsburg artists, and rumor-spreading wannabes—a Greek chorus of the cafeteria table. The books themselves would be narrated by Gossip Girl herself (or himself), an anonymous blogger with a gimlet-eyed take on the world around her. Or him.

Von Ziegesar began by modeling Gossip Girl on Edith Wharton’s The Age of Innocence, that earlier tale of a closed New York society. Serena van der Woodsen, a beauty kicked out of boarding school, returns to her old school, only to be dogged by envious rumors of lesbianism and love children. Von Ziegesar’s first draft was horribly high-minded, a fusty Wharton imitation; she quickly trashed it and adopted the brassy tones of Gossip Girl, who ends her dispatches with the teasing sign-off, “You know you love me.”

From the beginning, Von Ziegesar added her own raw and distinctive touches, not all of which went over with Little, Brown. In Gossip Girl No. 1, Serena falls serendipitously into modeling and—like Carrie Bradshaw—ends up pictured in bus ads all over Manhattan. However, unlike Carrie, the shots (at least in Von Ziegesar’s initial draft) were artistic close-ups of her anus—part of a series of shocking celebrity portraits. Little, Brown suggested Von Ziegesar substitute a belly button. She chose a compromise that works hilariously well—the orifice is itself a mystery, even to Blair, who is tortured by her former friend’s sudden fame. “Was it her belly button? It looked like the dark pit at the center of a peach … Blair could never get completely away—Serena was fucking everywhere.”

The author did no research among teens. “I don’t know what that says about me—that I didn’t mature?” she says. “Or, no, that’s not fair to the reader. It just says teenagers aren’t that different from adults.” Still, the books managed to be astonishingly prescient, picking up trends before the curve. In one plot, a freshman girl is filmed, thong exposed, during a Central Park makeout, only to have the footage ricochet across the Internet—a year before Paris Hilton’s sex tape. Von Ziegesar dramatized mean girls before Mean Girls, and picked up early on blogging, instant-messaging, micro-celebrity, and the kudzu-like growth of Hollywood gossip itself.

And despite Von Ziegesar’s stated intentions, her books do seem to teach their readers a lesson of sorts. For all its cynicism, Gossip Girl might be seen as a blueprint for reputation management on a massive scale—whether sudden fame or sudden notoriety. Serena is an effortlessly lucky flake, but she’s also an exceedingly benign individual, a role model for rising above jealousy: Never respond, smile pretty, feel no shame, expect attention as your due, and move on to the next bit of good luck.

Meanwhile, despite having scandalized her old school—where her headmistress was not thrilled to have her students portrayed as party girls—Von Ziegesar has made amends. “They have a different headmistress now, who was a little wary of me,” she says. Then Von Ziegesar wrote an essay for the Nightingale-Bamford school paper, describing her “warm and fuzzy” feelings for her alma mater. “She wrote me a nice letter saying, ‘I always thought you were like the girls in your books, but now I realize I was wrong.’ And she said, ‘Thank God.’ ” Von Ziegesar laughs—then looks thoughtful. “Still, it’s funny. They’ve never invited me once to their book fair.”

It’s the kind of slight the hypersensitive Blair Waldorf might take to heart. But when I visit the author in suburban Irvington, she warns me that she isn’t exactly living Blair’s life. Indeed, the lovely but reasonably sized home Von Ziegesar, 34, shares with her husband, a manager at a public art fund, and their two children (8 months and 3 years) is more kid-friendly than luxe. During our conversation, a workman drops by to inspect her leaking car. (“Try not to smoke near it,” he suggests.) The only sign of glamour is her cat, Pony Boy, a hairless creature who crouches by her side, gazing at me like a basilisk.

I compliment Von Ziegesar on her productivity. She’s planning to write her first non-YA book—possibly about motherhood. With the latest Gossip Girl in stores, another one due out in October, an infant, a toddler, and the spinoff series The It Girl in the works, it seemed like an amazing output. How are you doing all this? I asked. And that’s when the real gossip came out.

“I’m not writing The It Girl—did you know that?” Von Ziegesar blurts. “You keep talking about how I’m going to be so busy—but I’m not. It’s going to be ‘created’ by me, but use someone else’s writing.”

Alert “Page Six”: Just as her series reaches its highest pitch, Cecily von Ziegesar is getting out of the young-adult business. October’s edition (Gossip Girl No. 8: Nothing Can Keep Us Together) will be her swan song. After that, anonymous ghosts will pick up the quill, and Von Ziegesar will “oversee” the remaining books, and give notes on The It Girl, in which busty wannabe Jenny decamps for boarding school. But on both series, the byline will read “Created by Cecily von Ziegesar.”

“My editors will be like, ‘You bitch!’ ” she frets after the revelation—understandably, since such sausage-making scenarios are at once taboo and everywhere in the YA industry. (Hey, V. C. Andrews kept publishing after she died!) But it’s rather like Von Ziegesar to make explicit social complications others might politely kick under the carpet. She’d love to end the series; she knows it’s not hers to end.

Still, if she’s exiting the field, Von Ziegesar’s books have already altered the industry, catalyzing a legion of imitators, from Summer Boys (Gossip Guy) to Alloy’s own The A-List (Gossip Girl in L.A.) and The Clique (Gossip Girl in Westchester). Each aims to capture that Gossip Girl mystique; none quite hits the mark. Sure, they’ve got the ingredients—money, bitchiness, cliques, couture—and they are selling just fine. But these copycat series lack a tart and distinctive Von Ziegesar–iness, her appealing brand of cynicism—a cynicism that feels authentic, and also, oddly enough, compassionate.

Merely copying Gossip Girl’s coarser elements seems to miss the point. Von Ziegesar’s trademark is not, after all, her nasty streak, but her curiosity about the inner lives of the inner circle: She loves her meanest characters most of all. Although her fans may favor Serena, Von Ziegesar’s pet is the hilariously self-centered Blair, whose most generous daydream features her joining the Peace Corps, getting a killer tan, winning the Nobel Peace Prize, and having dinner with the president, “who would then write her a recommendation to Yale, and then Yale would fall all over themselves to accept her.”

So maybe it’s for the best that she’s thinking of writing about young moms—another world of aspirational ego begging to be punctured. She’s read The Nanny Diaries, and was disappointed in “this self-righteous educated nanny—I was more interested in the mother.” And she’s already bubbling over with acid candor on the subject, from the humiliations of finding a place to pump breast milk to playground politics. “I’d never really babysat. I feel like I’m Blair, or Gossip Girl. A teenager, basically—and now suddenly I’m a mom?” she says, wrinkling her forehead in amusement. “When I meet other parents and they’re more ‘mumsy’ than I am—you know, I don’t want to be ‘mumsy,’ but I’m like, ‘Were you always like that or … what happened?’”

Psst, Serena is a slut. Pass it on.