The Baby-sitters Club: Kristy Thomas, Mary Anne Spier, Claudia Kishi, Stacey McGill. They were the originals, the quartet of female friends who preceded the ladies of Sex and the City and came well before the foursome in Girls. They were also, of course, much younger: When we meet them (and some of them meet each other) for the first time in Book 1, Kristy's Great Idea, published in August 1986, they are 13 years old, seventh graders. They eventually graduated to eight grade, where they live out the duration of the series, written by Ann M. Martin and ghostwriters over a period of nearly 15 years. In the last book, published in October 2000, the girls finally graduated from middle school.

Though the series, as conceptualized by Scholastic editor Jean Feiwel and pitched to Martin, was originally planned as just four books, the success of the first few meant that requests for more quickly followed. All in all, the series came to consist of approximately 250 titles, including a prequel, The Summer Before, plus Mysteries, Super Specials, and the Little Sister and Friends Forever franchises. There have also been TV shows and films, and four of the books have been made into graphic novels by Raina Telgemeier. Lisa Simpson was inspired to babysit by The Babysitter Twins books, a clear homage. And there were and are countless real-life baby-sitters clubs—groups of girlfriends in poster-clad bedrooms sitting with their plastic hamburger phones-now-iPhones and notepads-or-maybe-iPads, waiting for the job calls to come in—all inspired by the initial monthly paperback series.

From the original foursome sprung more characters, club members including Dawn, the new girl from California; Mallory and Jessi, the younger girls; Logan, the honorary boy member and Mary Anne's boyfriend; and later members Shannon and Abby. Along with the main characters and their gradual development throughout the series, we were immersed in the world of Stoneybrook, Connecticut—the kids being babysat, the family members and friends of the girls, the school that they attended and its teachers, the neighborhoods, the lifestyles. There were so many books, and so many details (hair and eye color, number and names of the various siblings and babysitting charges, hobbies and habits and qualities and family situations), that David Levithan, now Scholastic's editorial director and a Y.A. author himself, was, as a 19-year-old intern working on the series, tasked with keeping a "bible" so that nothing would be mixed up or forgotten: "The first rule was making sure everything stayed faithful to that world," he told The Atlantic Wire. "I was the guy on the subway not only reading the BSC, I was reading it with a highlighter to keep track of who spoke French, who had green eyes, and so on." Later, that "bible" was published as The Complete Guide to the Baby-sitters Club

When Levithan started at Scholastic, the series "was already a juggernaut," he says. "I was not very familiar at 19, but I'd heard of it. I was plunged into the world of Stoneybrook, Connecticut, and I found I think like a 13-year-old girl very well! It was amazing to see that it was a fully embodied world to Ann and the editors and the readers. People knew it was fictional but it felt real."

A few times a year, Martin would plot out story ideas with her Scholastic editors, Levithan explains. They'd draw on their own childhood experiences, "always telling new stories and not just the same one over again. It gets harder and harder as it goes," he says, laughing. "We knew if we sat in the meeting and were like, 'Baby-sitters in space!' that would have been the sign of it jumping the shark. We did eventually get to the point that we felt the girls should graduate from eight grade, and that's the final book, but we found the desire was still there many years later and talked to Ann and came up with a prequel to go back into the world and introduce it to a new generation. We want to keep it alive and well, with repackaging, and a few other things coming down the pike." In odd perks of the job: Levithan got to name one character, Cary Retlin, after his best friend—"he showed up a few times, and in the years after, he'd tell me, 'Someone saw my name.' It's always fun making your best friend the arch villain."

Along with serving as easily-digestible monthly installments of sheer reading pleasure, the books taught a lot of girls (and boys, too—"there was a sort of boy babysitter underground," says Levithan, though the audience majority consisted of girls) lessons of empowerment, entrepreneurialism, and individualism. For some of us, the series also taught us how to love reading, and maybe even how to write. It immersed us in the world of Stoneybrook, Connecticut, and gave us a taste of what we might be able to accomplish in our own lives—it also taught us how to deal with common problems teens might face, ranging from the simple (annoying sisters and brothers, trouble at school) to deeper social and cultural issues, like coping with chronic illness, parents' divorce and remarriage, and racism. It's surely not surprising that this writer was a big fan of the series, but so were many others, including some of the editors who worked on the books at Scholastic.

Aimee Friedman, a senior editor at Scholastic and a bestselling Y.A. author herself, told me her first introduction to the series occurred when she was 8 or 9, via the Scholastic Book Club. "It was love at first sight," she says. "Those initial four girls, it's a brilliant setup, pre-Sex and the City: I'm a Stacey, I'm a Dawn, I'm a Mary Anne. I loved the premise of girls starting their own business, without even realizing it at the time. I was already a big reader, but I think it sparked in me an even bigger love of reading and writing. I owe a huge debt to Ann Martin for that inspiration; she makes it look easy." Later, working at Scholastic, she got to meet Martin: "I think I might have scared her a little," she says. "She's very shy: she always says she's a Mary Anne. She's lovely, such a nice person. I was like, 'I am your biggest fan!' I bet she gets that all the time. But now, in writing my own books, I tap into that young Aimee being so excited about BSC, having that pure passion."

Mallory Kass, another editor at Scholastic and writer of books for kids and teens, says the books turned her into, first and foremost, a reader. As family lore has it, she adored them so much that she read them at nearly all times, including at her own birthday party when she was eight. Her mother, the story goes, had to confiscate the book. It all started when a visiting, slightly older cousin introduced Kass to the series, and she "was hooked into that world and those characters, consuming them with a voracious hunger. I don’t think I aged out until Book 70," she says. "I was at Stoneybrook Middle School for 8 years, just like they all seem to be." 

The appeal was the independence of the characters, that they could be entrepreneurial and mature, but also, that they were kids living pretty great adolescent lives. "They had this really inspiring self-assurance that I think I definitely associated more with adulthood than with adolescence, but they still had pizza parties and sleepovers; Kristy would still snort milk out of her nose," says Kass. At the same time, the books tackled "broader social issues, racism, with Keep Out Claudia, and eating disorders with Jessi, but also simpler issues I was going through: Mallory hates boys and gym." Friedman agrees, "The series dealt with difficult topics—Stacey had diabetes, parents were divorced, Jessi was dealing with racism. But it wasn't done in a preachy way, which I think kids are allergic to. I could see hesitation nowadays about having a character with a chronic illness, but I think BSC paved the way for making that OK."

Friedman adds that she loved the pro-girl, pro-female (and not cruel) friendship model represented in the books. "They still have arguments, and there are interesting dynamics within the group, but it's totally relatable and not a cookie-cutter view of the world." Also appealing is that the characters each represent parts of us. "Everyone has a Kristy, everyone has a Mary Anne. You identify and see a bit of yourself in each of them," says Kass, but there's collectivism as well. "They come together more powerfully as a whole, and that’s a great thing to think about female friendships. They were each stronger and more able to be themselves with so many people supporting them." Friedman says, "I liked Dawn, she was fun and refreshing, from California, vegetarian, exotic. I also loved Boy-Crazy Stacey; I kind of related to Stacey, being from New York City."

Excluding the characters for a moment, are the books hopelessly technologically dated? It's hard to imagine a group of girls not using Facebook, for example, to help them start their club. But Levithan says those questions were considered when Telgemeier was writing the graphic novels, and "the fact is, the way that we did it was still the most efficient and safest way. Nobody would want them to put their cell phone numbers on a flier; you'd want a landline, you'd want parents involved. And websites, for a 13-year-old girl ... it's just better and more efficient to be in the same room." Beyond safety concerns, the books were not just about baby-sitting but about friendships, sitting together in a room and gabbing with the girls while running your own successful business, too. "Yes, Claudia might not be the only one with landline in her room," says Levithan, "and now, there probably wouldn't be a cord on it—but they'd still want to be together."

Speaking of things standing the test of time, no discussion of the BSC would be complete without a mention of Claudia's fashion sense, which, amazingly, seems to hold up incredibly well despite the books' '80s birthdate. "It was always amusing because I'd have to use J. Crew catalogs as explainers for what her wardrobe was, like, what are capri pants?" Levithan says. "But those outfits totally hold up! It proves that a fashion eccentric has timeless style; it's cool as long as you pull it off."

The series has influenced a range of writers, including the three editors I interviewed for this piece, as well as a form of writing for kids that focuses on character and friendships rather than simply on plots, à la Nancy Drew. Levithan says, "I don't think you could have Sisterhood of the Traveling Pants without BSC. Everything in that vein, really: If you look at Stephanie Perkins, Sarah Dessen, I don't know they were BSC readers, but I think the BSC reader went on to read those books. Jenny Han was a huge fan, and if you read her summer books you can see that."

Also, they're just wonderfully nostalgic for some of us, a comfort read that reminds us of our own childhoods. As Kass says, "I won’t give up my BSCs. I do re-read them when I go home [to my parents' house]. There’s something bittersweet but lovely about it; you're not just revisiting characters but a form of yourself, reminding yourself of who you were when you were entering that world." Friedman admits, "I will sometimes still peek into them. They're a good, cozy read. The core of the series are the relationships between those characters, and the idea of a club is timeless; spending time together and banding together to do something adult-like, having a group of girlfriends who get you, and you all bring your own thing to the table. The tech stuff falls by the wayside and is kind of beside the point, I think. For people like us, thirtysomething, twentysomething women, the books bring back so many great memories."

At the same time that we read them again and remember ourselves, there are new generations of kids who will be reading them for the first time. "I can’t wait for my 2-year-old niece to get old enough, so I can see how the next generation responds," says Friedman. Levithan adds, "They love it. I know some moms who are reading it aloud to their 8- or 9-year-old daughters; they're holding mother-daughter book clubs with it. What they're amazed at is how well it holds up, how the 9-year-olds of today still relate. I think it was important that the characters were the leaders in their own lives."