Highly successful and popular series of books aimed at pre-teen girls, about a group of kids who run a club that offers their services as babysitters. The series was written by Ann M. Martin and published between 1986 and 2000. It also inspired a 1995 film, a TV series and several spinoffs. Every story was told from the first-person perspective of the protagonist, and began with a description of the rest of the club members.In most of the books, the title club consisted of:
Kristy Thomas - Rags to Riches tomboy with an endless supply of "Great Ideas"
Janine Kishi - Claudia's genius older sister, alternately a source of frustration and support, but she wants to be supportive. Narrates in a Super Special.
Charlie Thomas - Kristy's responsible oldest brother, who often drives her and her friends around in exchange for gas money from the club dues.
Sam Thomas - Kristy's second-oldest brother, who often prank calls the club meetings and has a semi-mutual crush on Stacey. Narrates in a Super Special.
Jeff Schafer - Dawn's younger brother, whose homesickness for California and acting out was a running subplot between #9-#15. Narrates in a couple Super Specials.
Logan Bruno - Mary Anne's boyfriend from Kentucky and part-time club member. Narrates two "Special Edition Reader's Request" books and in several Super Specials.
Shannon Kilbourne - Part-time club member and rich-kid friend of Kristy. Narrates a "Special Edition Reader's Request" book and in a couple Super Specials.
Cokie Mason - Popular girl who was a rival to most of the club, who often attempted to win Logan away from Mary Anne
Laine Cummings - Stacey's best friend from New York.
Sunny Winslow - Dawn's best friend from California. A main character of the "California Diaries" series and source of much of the drama.
Anna Stevenson - Abby's identical twin sister.
There were at least three spinoff series: Baby-Sitter's Little Sister (about Kristy's seven-year-old stepsister, Karen); California Diaries (about Dawn and her friends in California); and Friends Forever (in which the club was reduced to its original four members). As well as these and the main series, there were additional Mysteries, autobiographical, and Super Specials books. Little Sister also had its own spinoff, The Kids In Ms. Colman's Class. As you might suspect, many of the books were ghostwritten, although Martin wrote the original 35 books herself.A prequel, The Summer Before, was released more recently, about the original four club members the summer before seventh grade and their lives right before they started the club, to coincide with the books being reissued.
The books provide examples of:
Abhorrent Admirer: Abby has one of these in one book. There's nothing wrong with the kid himself, but the trope fits in because she's really not happy about his interest in her.
Academic Athlete: Kristy has the management skills to create the club and be its president. Her sport is softball and she even starts a kids' team.
Added Alliterative Appeal: The softball teams that Kristy and Bart coach are called, respectively, Kristy's Krushers and Bart's Bashers.
Adult Fear: In Dawn and the Impossible Three, Buddy Barrett appears to have been kidnapped while Dawn is watching him.
Aesop Amnesia: A number of examples, but one that stands out in particular is the relationship between Claudia and her genius sister Janine. There are many books where the two of them bond over junk food, have a heart-to-heart talk, and realize that they're Not So Different. By the next book, their relationship is back to where it was.
Also a feature in many Little Sister books, where Karen learns not to be a brat only to promptly forget it by the time the next book comes around.
There were also multiple books where the sitters pushed Charlotte Johanssen into some sort of public performance, only for it to blow up in their faces and for them to have to apologize to Charlotte and her parents. Not only did they not learn any general lessons about respecting boundaries, but even the specific lesson, "Don't force Charlotte to do stuff she doesn't want to do," never seemed to sink in.
Adults Are Useless: Usually averted. The parents are generally pretty good parents, and the sitters will not hesitate to take advice from them. Sometimes played straight in the Mysteries series, if the girls going to an authority figure would break the plot.
However, also often played straight in that the parents of charges are frequently clueless about problems their children are having, until told by the BSC. For example:
Mrs. Arnold not realising that her identical twin daughters are acting out because they're sick of being treated like they're one person.
Mrs. Addison failing to realize that her kids want to spend some time with her instead of being dumped on sitters all the time.
Mrs. Barrett, when she's first introduced, is in the middle of an unpleasant divorce; as a result she is highly disorganized and does things like neglecting to leave the sitters with contact information and even forgetting to inform Dawn of one kid's allergies.
In a later book, Mrs. Prezzioso not noticing her older daughter's obsessive finicky behaviour and then acting out, as she was too distracted by becoming a pageant mom for her younger daughter.
In the Arnold and Addison cases, as well as a few others not mentioned here explicitly, the fathers are just as clueless as the mothers; it's just that the mother is the one doing most of the talking to the baby-sitters.
The Alleged Car: The Junk Bucket. Subverted with the Pink Clinker, which actually works well — Nannie just likes to call it that.
Shawna Riverson also, though she didn't appear as often.
In the Little Sister spinoff, Pamela Harding.
Always Identical Twins: Abby and Anna, Marilyn and Carolyn, Mariah and Miranda, not to mention the Pike triplets.
Ambiguously Gay: Ducky, in the California Diaries. His best friends are all platonic teenage girls, and his last scene in the series has him buying a ton of books from a bunch of gay authors.
Some fans suspect that Kristy fits this trope. She could occasionally be persuaded to wear a dress, and did have an on-off "boyfriend" named Bart, but never seemed to take as much of an interest in him as the other girls did with their own boyfriends (then finally broke up with him.) And in the movie, as The Nostalgia Chick noted, there's what can only be described as a Longing Look between her and Claudia.
David Michael and Karen, for Kristy. However, it's worth noting that Karen annoyed the readers more than she ever annoyed Kristy — Kristy and Karen are just different enough to get along and just far apart enough in age that their similarities (namely, being bossy and stubborn) don't come into conflict, since Karen hero-worships her stepsister. It helps that they only live together half the time, at most.
Dawn's brother Jeff, in early books.
All seven of Mallory's siblings qualify, except maybe Vanessa; but she has her moments too.
Mostly averted, though, with Jessi's younger siblings, Becca and Squirt.
Arc: Some plotlines spread over a couple of books, such as Kristy adjusting to her stepfamily. At the end of the series Mary Anne's house burned down, which was the background for the Friends Forever spinoff.
The Dawn-considers-moving-back-to-California plotline lasted for so many books that many fans were extremely glad when she ultimately did move back and she finally stopped agonizing about this decision.
Author Appeal: Ann M. Martin had the girls, as well as their classmates and the kids they babysat for, watch the same TV shows and movies she enjoyed as a child. The result is a bunch of preteens from The Eighties and The Nineties whose pop culture references mostly come from Leave It to Beaver, I Love Lucy, and other shows that were canceled decades before they were born.
Possibly Author Appeal, but more likely Truthin Television because the books were written for the most part in The Eighties. At the time kids were watching reruns of classic sitcoms because basic cable stations, especially the TBS Super Station and USA Network, showed them nonstop as a source of cheap daytime programming filler. Additionally, Nick At Nite debuted in the mid-80s and took over children's programming with reruns of these same sitcoms starting at 8 PM.
Bratty Half-Pint: Karen. Dear god, Karen. Jenny Prezzioso is seen as such by the sitters.
Bratty Teenage Daughter: Dawn has probably the worst example of this trope in Here Come the Bridesmaids! when her father is getting remarried. She all but pitches a fit because her stepmother-to-be doesn't want to have Mary Anne as a bridesmaid as well as Dawn. Remember, Mary Anne is Dawn's stepsister on her mother's side and is not remotely related to Dawn's father, let alone his new bride.
Keep in mind that Dawn never asked if Mary Anne could be a bridesmaid. She just assumed that Mary Anne would be sharing the moment with her and bought her a dress. To Dawn's credit, she never brings up her (frankly, stupid) assumption to her father or stepmother. But Mary Anne still ends up wearing the bridesmaid dress, because she assumed it'd be a church wedding, not a beach wedding, and didn't pack appropriately. One has to wonder just what Dawn's father and stepmother thought about that.
Kristy has shades of this in the earliest books in the series, when she is flat-out opposed to her mother's developing relationship with Watson. She insults the man, refuses to eat dinner when he treats them, and is generally unpleasant. It seems to be less a matter of her disliking Watson personally than a desire to keep her fractured family from experiencing any additional changes. To her credit, she warms up to him eventually (finally meeting Karen and Andrew helps) and in a later book admits that she loves him a lot.
Busman's Holiday: Probably the worst example was when the girls were in New York and a British diplomat oh-so-conveniently staying in the same building as Stacey's friend Laine needed two thirteen-year-old baby-sitters to show his kids around the city.
They even assume that they will be taking a Busman's Holiday wherever they go, such as when Dawn goes to visit her dad in California and remarks that she may babysit for some of her old clients while she's there. You know, because their parents wouldn't have found new sitters since she left the state, and would be so thoughtless as to intrude on her two weeks with her non-custodial parent by asking her to work.
Christmas In July: The BSC throw a "Christmas in Summer" party for sitting charge James Hobart, who is Australian, to cheer him up when he has a broken leg. This happened again at summer camp.
Chuck Cunningham Syndrome: This is pretty much the case for most of the girls' non-BSC friends, with the major exceptions being Laine Cummings, Stacey's on-again, off-again best friend from New York, and Sunny Winslow, Dawn's Troubled, but Cute best friend from California. But Sunny started her own baby-sitting club, anyway, so she doesn't really count.
Class Trip: Several, most notably the school-wide ski trip.
Clingy Jealous Girl: Dawn shows a dose of this in Mary Anne's Makeover, in which she admits that she's jealous of all the time Mary Anne's been spending with her father and that it makes her miss her own terribly. Dawn comes off as being resentful of Mary Anne for having her father around...apparently forgetting that this is Mary Anne's only living parent.
Costume Porn: Any given book will have several detailed descriptions of all the girls' outfits, but especially Claudia's. There's usually a shopping trip to the local mall, too, which enters Fridge Logic territory when one wonders how they manage to afford all that stuff on their $4.00-an-hour babysitting gigs.
Darker and Edgier: The California Diaries series. However, the use of this trope surprisingly didn't come off as cheesy or overdone. It allowed for more character development and exploration of realistic adolescent themes, like depression, drifting away from childhood friends, and (arguably) closeted homosexuality.
Disappeared Dad: Kristy's father, Patrick Thomas, abandoned his wife and four children and almost never calls or writes.
Does This Remind You of Anything?: The whole plotline about Stacey's diabetes and the associated stigma leading to her moving away from New York lest she lose all her friends. In retrospect, the series' origins in the late eighties makes it likely the diabetes stood in for something else.
It's mentioned constantly that Mary Anne's father loosened up considerably when he started seeing Dawn's mother. Adults rereading the series might read between the lines a bit.
One of their classmates, Amelia, is killed by a drunk driver in Mary Anne and the Memory Garden.
Abby's father was killed by a drunk driver prior to her series debut. According to Abby's Book, his death is the reason their mom moves Abby and Anna to Stoneybrook in the first place — to distance herself from the memories.
Everyone Loves Blondes: There are two out of four white girls from out of state: Stacey, the sophisticated New Yorker, and Dawn, the breezy Californian. Lampshaded in one book where Kristy reminisces about how she first met Shannon (whom she intensely disliked at first) and snarks about the trope in relation to Shannon and her friends, who are all blonde.
Failure Is the Only Option: The BSC were allowed to succeed most of the time, but once the problems got big, like trying to keep an autistic savant from being sent Off to Boarding School or reform a racist family, the Aesop was always along the lines of You Can't Make A Difference When You're Thirteen Years Old. Little Sister was even worse about this, with Karen failing at nearly everything she tried to do because You Really Can't Make A Difference When You're Seven Years Old. The only time Karen actually succeeded was during a Whole Plot Reference to The Secret Garden, since you can't very well have your Mary Lennox surrogate not shake things up.
Fan Nickname: "K. Ron" (after L. Ron Hubbard) for Kristy and "BSCult" have become popular on some snark communities.
Five-Token Band: Let's see. We have a Japanese-American girl, an African-American girl, a boy, three girls with divorced parents, two girls with one deceased parent each, one Jewish girl, a diabetic girl, and an asthmatic girl... and that's just in the club itself.
Flanderization: All of the girls' quirks suffered this to some degree with the ghost writers, most notably Kristy's bossiness, Dawn's passion for environmental causes and Claudia's bad spelling.
Margo Pike's motion sickness. In Boy-Crazy Stacey, Margo almost gets car-sick on the way to Sea City but feels better once she moves to the front seat. Somehow, this turned into pretty much her only character trait, to the point where it was surprising she could walk down the street without getting sick.
Food Porn: Especially prominent in Dawn and Claudia books.
Four Girl Ensemble: The original four members: Kristy is known for her leadership skills and great ideas, which along with her outgoing nature make her a good softball coach. Mary Anne is good at being organized but she has a sensitive and shy nature. Claudia is a passionate artist and is known for her creativity and fashion sense as well as being boy-crazy. Last of all there is Stacey who is like Claudia but a more sophisticated math genius who is looked up to because she's from New York.
Free-Range Children: The club themselves are actually the worst offenders of this. Whenever these eleven- and thirteen-year-olds go on vacation, they're allowed to roam around freely without adult supervision, even in New York City.
Frozen In Time: The girls spent literally dozens of birthdays, holidays and summers in eighth grade. At one point Claudia was demoted to seventh grade, but the others stayed in place. They finally finished middle school in the last book of the Friends Forever spinoff.
In one of the 2010 reissues, "thongs" was changed to "flip-flops", for obvious reasons.
Logan also says "I decided to act as if I’d seen a million little kids fly through the air and nearly cream themselves on pianos, though" when Jackie Rodowsky (who else?) leaps off the couch and nearly crashes into the piano in Super Special 11: The Babysitters Remember.
Not to mention the harmonica going "WAAAAAAAAAANK!" in Stacey vs. the BSC.
And in one book, a particularly big crying fit by Mary Anne was described as "Mary Anne became a gusher."
Jerkass: Kristy's dad is portrayed this way in the Forever Friends book where he remarries, and even moreso in The Movie. It's also hinted at in Claudia's Book, where she notes that as a little girl she seriously disliked Mr. Thomas.
Just Friends: One book was based around Kristy's relationship with Bart and whether or not they would become an Official Couple. Kristy finally decides they should remain "just friends" when it becomes clear that Bart expects more from the relationship than she wants.
Kid Detective: There was an entire spinoff Mystery series based on this trope.
The classmates of the baby-sitting charges (especially Charlotte's classmates), though this is existent in the BSC's classmates as well, especially in Mallory and Jessi's sixth grade class.
Some of the charges have this too — though mostly they're of the prank-playing kind. One of Claudia's charges once played a prank where she didn't tell Claudia that the chain of a swing was broken, thinking it'd just break under Claudia's weight when she sat on it. Instead, it held, the kid forgot to warn her, and the chain finally broke mid-swing, leading to Claudia breaking her leg so severely, she had to stay in the hospital with the leg in traction. The rest of the book switched between Claudia recovering and the club joining forces with some of their other charges to get the kid to stop playing pranks.
The Klutz: Jackie Rodowsky, AKA "The Walking Disaster"
Law of Disproportionate Response: The Club had Andrew, who was pretending to be a monster, terrify the life out of one charge because she didn't want to wear a smock and paint.
Jessi accused one kid of being racist because the kid didn't want to play.
Least Common Pizza Topping: In one of the specials, where Stacey describes how while in New York she invited her new friend to a sleepover at Laine's. Laine and the others disliked the girl, partly because she asked for anchovies on the pizza they ordered.
It's a minor running gag that the sitters have incompatible pizza needs, especially once the club has the classic seven-member lineup - early on, Stacey couldn't eat processed cheese; Dawn won't eat meat; Abby is allergic to both tomatoes and cheese; Kristy likes anchovies, etc. Mary Anne and the Playground Fight has this get uncivilized to the point where they all just order separate meals, while Abby and the Mystery Baby has the Genre Savvy Abby order a plain pizza and she just prepares the other toppings at home, letting her friends do their individual slices as they please.
Lighter and Softer: The Little Sister series. The Kids In Ms. Colman's Class was even lighter and softer than that.
Littlest Cancer Patient: In Jessi's Wish. Other books had children with deafness, Down's Syndrome and autism. In one of the Super Specials, Stacey befriended a wheelchair-bound boy who was about to have surgery for a heart condition. May extend to Stacey herself, who was diabetic. In another book a babysitting charge has to adjust to blindness. Abby and her twin sister Anna both have scoliosis, but while Abby's is mild, Anna's is severe enough to require her to wear a brace to correct it.
Appears pretty much whenever the girls deal with something weird. They usually get a mundane explanation that covers most, but not all, of what's been going on. Particular examples would include The Ghost at Dawn's House and Mary Anne's Bad Luck Mystery.
Also, the first book in the Little Sister series, where the only undebunked evidence Karen has at the end is that she saw the lady she thinks is a witch flying on a broom... and that might have been a dream. A later book in the series had Karen suspect that Mrs. Porter's granddaughter, Drusilla, is also a witch. Drusilla later admits she's not, but says she's never been sure about her grandmother ...
Also probably completely unintentional, because Claudia is named after Dr. Claudia Werner, a friend of Martin's who consulted on Stacey's diabetes and had #3 dedicated to her, "Claudia" is derived from the Latin for "lame." Given her learning difficulties, this borders on Unfortunate Implications.
Melodrama: There's no other word to describe the scene in Boy-Crazy Stacey where the girls are saying goodbye. They're all going their (temporary) separate ways and the waterworks are endless. Sobbing, hugging, wailing. How long will they be apart? Two weeks.
Mood Whiplash: Claudia and the Terrible Truth, where the Very Special Episode-esque main plot (the girls finding out that two of their new charges are being abused by their father) is interspersed with the sitters helping kids preparing for a St. Patrick's Day parade.
Non-Human Sidekick: Several, although Mary Anne's cat Tigger is probably the most frequently showcased — partly because Mary Anne, unlike the others, is an only child.
No Periods, Period: It's plausible for a thirteen-year-old girl not to have started her period yet, which makes a reasonable justification for the trope, but it's decidedly less plausible that none of them would have started menstruating by that age. Presumably it's not mentioned because the target age range for the books was a bit younger than thirteen, and they didn't want to freak out the kids (or their parents).
No Pronunciation Guide: Is Myriah Perkins' name pronounced like "Maria" or "Mariah"? Fans can't seem to decide.
Not Allowed to Grow Up: The first few books show the passage of time as the original five complete seventh grade and start eighth, but once they're in eighth grade, they stay there until the last book of the series finally lets them graduate.
Playing Pictionary: It is suggested that one say something along the lines of "What a nice picture! Can you tell me about it?" when confronted with a child's drawing, because "you don't want to say 'what a lovely elephant!' and have it turn out to be a picture of their grandmother."
Poisonous Friend: Ashley, who encouraged Claudia to leave the club and spend more time on her artwork. Also the "bad girls" group that Stacey falls in with later in the series.
Polar Opposite Twins: Abby and her twin sister Anna. Anna is musical, bookish, and introspective; Abby is athletic, noisy, and enjoys babysitting. About the only things they have in common are that they both have scoliosis and poor eyesight. Interestingly, this never creates a conflict between them— when they first realized they had branching interests as little girls, their initial reaction was to panic and double-down on making sure they had identical everything. They did grow out of that, because while they liked being identical, they didn't like being treated as a single entity and didn't want to chain themselves down to being completely identical when they realized that having separate interests wouldn't create a break between them.
Protagonist-Centered Morality: In book #12, the girls get bitchy over Claudia spending time with a new friend and go as far as to short-sheet her bed, mess with her belongings, and leave her a series of nasty notes. But in the end, Claudia is the one who owes them an apology for "being a bad friend."
The girls also viciously shun Mary Anne in another story after she commits the mortal sin of... getting a stylish new haircut. Everything's back to hunky dory by the end of the book.
Stacey's parents treat each other so hideously in the period leading up to their divorce that it stresses their daughter out until she winds up hospitalized - and they continue sniping at each other in her hospital room. She finally loses her temper and yells at them to shut up. Instead of this making them realize just how childish they're being, they yell at their sick child; nor do they ever apologize to her for it.
In one book, the girls are angry and hurt when Mrs. Newton decides to hire an older sitter for her new baby as she feels that a 13-year-old, no matter how experienced, may not be able to cope with a newborn. The girls act like it's irrational and unfair, and the girls do eventually prove that several of those sitters are Very Bad, although Mrs. Newton says she found one she liked and she'll continue to call him on his own. The girls do eventually get to sit for Lucy Newton, but not until they're in eighth grade.
Real Men Hate Sugar: In one of the books when Nicky Pike and Buddy Barrett refuse to eat cookies after having been teased for attending a "girly" sewing class.
Retcon: Early on, Jill, a member of the We ♥ Kids Club, is established as serious and thoughtful; at one point, Dawn describes her as being like Mary Anne. In the first California Diaries book she is portrayed as very childish, which contributes to Dawn, Maggie and Sunny drifting away from her.
The Brewer children's mother and stepfather are named as Sheila and Kendall in an early book, later retconned to Lisa and Seth when they feature more prominently in later titles.
Similarly, Mary Anne's late mother was named Abigail in the fourth book, but later books identify her as Alma. This is also fixed in reprints.
There was a short spinoff series where each of the girls writes an autobiography. They must have been written by different writers, because Kristy, Mary Anne, and Claudia have conflicting memories of their elementary school years (when they all knew each other).
In the early books, Dawn is a semi-vegetarian who eats chicken and fish; she avoids red meat because she thinks it's unhealthy and doesn't like the taste. She specifically says in one book that her vegetarianism DOESN'T have anything to do with feeling sorry for cows, and in fact she doesn't even like animals all that much. This is somewhat hard to reconcile with the radical environmentalist she is in the later books.
Dawn gets hit hard by this. Early books also show her and her father as very organized and practical, as a contrast to her absent-minded mother. She's not as organized as Mary Anne, but she's close, and Jack Schafer plans a trip to Disneyland like a war campaign. But after her mother marries Mary Anne's father, Dawn and her dad both get hit hard by the "California casual" stereotype. They're never quite as bad as Sharon, but they're written to contrast with Mary Anne and her extremely organized father.
Rich Bitch: Shannon Kilbourne started out as this, although it was less because she genuinely looked down on Kristy and more because she didn't want Kristy and her friends to take away her baby-sitting jobs.
The Rival: Cokie. Also, one book featured the girls facing off against a rival babysitting club.
Second Place Is for Winners: Little Miss Stoneybrook...and Dawn had the sitters helping their charges prepare for a beauty pageant. First prize was a savings bond and the chance to compete in another pageant. Second prize was a shopping spree at a local toy store. Unsurprisingly, all the 6-to-10-year-old girls entered in the pageant massively prefer the second prize. As the eventual second place winner explains to all the adults who are indignant about the fact that she didn't win, "But then [if I had won] I wouldn't get any toys!"
Self-Deprecation: Claudia and Mallory, for very different reasons, are the most prone to this.
Shrinking Violet: Mary Anne; Kristy's little stepbrother Andrew is presented this way too.
Spell My Name with an S: It's Stacey, Jessi, and Mary Anne, not Stacy, Jessie, and Mary Ann/Marianne/Mariann/Maryann/Maryanne/Mary-Ann/Mary-Anne/etc.
Spinoff: The Little Sister and California Diaries series. The Kids In Ms. Colman's Class is a spinoff of LS.
Spoiled Brat: Jenny Prezzioso; to many fans, Karen Brewer also qualifies.
Start My Own: When the BSC goes crazy testing Mallory about whether she's a good enough sitter, she and Jessi start up "Kids Incorporated."
Straw Fan: Believe it or not, one of the books deals with Mallory claiming to be the biggest fan of a fictional children's author, meeting the author and giving her a hard time about not 'writing what she knows.' Fortunately, she learns her lesson in the end.
Superstition Episode: There's a book where Mary Anne thinks she's gotten a bad luck charm. It turns out some cruel girls just told her it was bad, and were using it as an excuse to play pranks on her.
Surprisingly, though, with such a high IQ all they have her do is take a few courses at the local community college.
Theme Twin Naming: Marilyn and Carolyn Arnold, Abigail and Anna Stevenson, Mariah and Miranda Shillaber, Terri and Tammy Barkan, Ricky and Rose Salem. Averted with the Pike triplets Adam, Byron, and Jordan.
Twin Switch: Marilyn and Carolyn did this once while Mallory was babysitting.
Two First Names: Kristy Thomas; Logan, Hunter and Kerry Bruno; Marilyn and Carolyn Arnold
Unishment: When Mary Anne tries to sneak over to the boys' side and Logan starts a food fight at summer camp, they are punished... by being barred from their least favourite activities.
Very Special Episode: Several books showcased a particular social issue, including racism, hazing, eating disorders and single parenting. They did not deal with topics like illicit drugs and sexuality, and only briefly touched on alcohol, which might have been considered inappropriate for the target audience.
Viewers Are Goldfish: The main characters got repeatedly introduced and described in every book. Lampshaded by the various snark communities as being the standard contents of chapter two.
Wedding Day: Kristy's mother and stepfather, Mary Anne's father and Dawn's mother, Dawn's father and stepmother, two sitting clients, Kristy's father and stepmother ...
What Could Have Been: A planned spin-off would have been called Morbidda Destiny, Teenage Witch, based on Karen's belief that her elderly neighbor Mrs. Porter was a witch whose real name was Morbidda Destiny; but the idea didn't do well with test groups and was scrapped.
Stacey's dad is a workaholic who rarely spends time with her.
Abby's mother is like this too. Possibly justified to an extent, since she's a single parent with two teenagers to support.
Shannon Kilbourne's father is never home, either.
One book had a subplot in which the sitters begin taking care of two kids who are constantly forced to attend extra-curricular classes and sports activities because their parents are basically selfish flakes, and all they ever want is time for themselves, so they shuttle their son and daughter off to every extracurricular possible (even, at one point, practically forcing Claudia to put together an art class for neighborhood kids just so they could put their daughter in it).
Wicked Witch: Karen Brewer believes that the next door neighbor Mrs. Porter is one, and that her real name is Morbidda Destiny. The sitters would waver on whether or not they really believed this (and one of the Little Sister books revealed that even Mrs. Porter's granddaughter could not be sure whether it was true). Kristy eventually reasoned that Mrs. Porter could not be a real witch because when the Brewers' cat left a dead mouse on her doorstep she brought it over to demand that they dispose of it, rather than keeping to use in her potions.
Writers Cannot Do Math: The number of bedrooms in Watson's house never seems to add up. Kristy says his house has 9 bedrooms, which should mean one each for Watson and Elizabeth, Kristy, Sam, Charlie, David Michael, Karen, Andrew, Emily Michelle and Nannie. However, in another book Kristy says that each of her brothers could have a whole suite of rooms if they wanted, and occasionally they've had entire families stay over with no discussion of people moving or sharing rooms.
It may be that the "9 bedrooms" refers only to the bedrooms on the first and second floors. It's mentioned that there is a third floor and an attic that are never used (which is most certainly not because the ghost of Ben Brewer haunts them), so her brothers could have suites, but would have to move to the upper floors. Presumably, these upper floors are where house guests are quartered for the duration of their stay.