Adults Are Useless: Annabel's parents have no idea Whitney has an eating disorder until she freaks out at a family dinner (and numerous hints were dropped by Kirsten. They also don't know Annabel was molested by Will Cash until near the end.
Caroline Dawes in Keeping the Moon. Bea Williamson is an adult version.
Alternate Character Interpretation: In-Universe in The Truth About Forever. Everyone views Monica as an unfeeling slacker. Her sister Kristy, however, believes that she purposefully closes herself off from people due to survivor's guilt for not being in the car crash that scarred Kristy and killed their mother. We are never given definitive answers for this, but it's implied that Kristy is right.
In-Universe in That Summer as the Mc Phail women attempt to decipher the actions of their father's new wife, Lorna. Haven thinks she's mostly mean with a hint of stupid, Ashley doesn't think she's mean at all, just really stupid.
Always Someone Better: Macy believes this about Amanda and Bethany, two other girls who work at the library, until Kristy points out otherwise.
Haven feels her older sister Ashley is this.
Amazingly Embarrassing Parents: Halley's dad in Someone Like You gets a job hosting the local radio, where he tells humiliating stories about Halley that her school hears. Not to mention her mother publishes books about her and Halley's relationship. It's a large factor in why their relationship is so precarious.
Annoying Younger Sibling: Mallory, Owen's little sister in Just Listen. Owen thinks she's annoying, Annabel thinks she's cute. Also, even though she is only a baby, Thisbe in Along for the Ride.
Jake in Along For the Ride.
Anti-Hero: Auden and Ruby are the most obvious examples, particularly the latter.
Armour Piercing Question: Near the end of Someone Like You, Halley ends up in the hospital because of Macon's bad driving. When he shows up at Halley's house, she promptly breaks up with him, not only for that but also constantly pressuring her to have sex with him. When she goes back inside, her mother immediately starts yelling at her, telling Halley she won't let her ruin her life because of Macon and threatens to transfer her to another school. Halley interrupts her with, "Why don't you ask me what I said to him?"
In The Truth About Forever, Macy and Wes bond over asking one another these types of questions. Since she reveals her biggest secret to him so early on, Macy feels much more comfortable with him than anyone. Near the end she asks him what he would do if he could do anything and he doesn't answer her. Later she has him ask her the same question and her answer is to kiss him.
Someone Like You: Scarlett faces being ostracized in school when she decides to keep Micheal's baby
The Truth About Forever: Delia's pregnancy causes problems for her catering business (and she sometimes neglects her toddler, Lucy, as well)
Along for the Ride: Auden is initially irritated and wary of Thisbe. Also, the stress of caring for a newborn is putting serious pressure on her dad and Heidi's marriage, especially because her father refuses to help with most of Thisbe's care.
What Happened to Goodbye?: when Mclean's mother has twins with Peter, Mclean feels rejected and resentful of them.
The Moon and More: Emaline's back story involves her mother giving up everything to have her while still in high school, including being ostracized by the town, being let down and heartbroken by Emaline's father, and being treated horribly by Emaline's father's family. Her life eventually got better after she grew up and married, but it was a long, painful journey.
Bait and Switch: Ruby's mother is reportedly found near the end of the novel, and for a little bit it seems like Ruby is thinking of finding her to confront her, but this never happens.
Will Cash from Just Listen, but in a different way.
Mark, Morgan's fiance in Keeping the Moon.
Beast and Beauty: Annabel and Owen in Just Listen are mocked for this when they first begin spending time together.
Beauty Is Never Tarnished: Subverted with Kristy. Kristy's beauty was completed tarnished by a car accident but the more Macy and others get to know her, they find her inner beauty shining through and don't even notice the scars anymore.
Hollis and Lauren in Along for the Ride. Heidi and Auden's dad could also count.
Mclean's dad and Opal in What Happened to Goodbye?
Daisy and Morris in The Moon and More.
Big Sister Instinct: They may bicker from time to time, but Kristy does not like people slagging off her sister Monica and defends her at every opportunity, probably because she knows Monica won't.
Kirsten to Annabel and Whitney; She defends the latter when Sophie is mean to her the first day they meet, and she's the one who tell their parents about Whitney's eating disorder, even though the latter hates her for it for a while.
Cora went out of her way to protect Ruby when they were younger and spent years afterwords trying to get back in contact with her. Then she agrees to take care of her once it becomes clear their mother has abandoned her.
Wes is very protective of Bert and claims Bert is what he worries about the most.
Catchphrase: Pick a Sarah Dessen novel. Any of them. In every single one of them, the phrase, "I just looked at him/her." will pop up. Also, female characters always seem to be tucking a piece of hair behind their ears.
Character Development: Happens in all of the novels. Jason Talbot noticeably develops between Along for the Ride and What Happened to Goodbye.
Character Overlap: Frequently. The ones listed below are rare in how explicit the cameos are.
Scarlett from Someone Like You appears in This Lullaby.
Remy, Dexter, and the The Truth Squad from This Lullaby cameo in Just Listen.
Jason Talbot from Truth About Forever reappears in Along For the Ride and What Happened to Goodbye.
Heidi and Thisbe from Along For the Ride in What Happened to Goodbye.
Auden, Heidi, and Maggie from Along for the Ride show up in The Moon and More.
Any story taking place in Colby (Keeping the Moon, Along for the Ride, The Moon and More) is going to have a lot of overlap (like the Last Chance diner, Clementine's boutique, Abe's Bikes, etc.)
Clingy Jealous Girl: Belissa in Along for the Ride. The strange thing is, she's the one who broke up with Eli.
Heather from Lock and Key is an aversion. She broke up with Nate, but still expresses friendly concern for him afterwards to Ruby.
Clueless Chick Magnet: Subverted with Wes. He is aware of all the girls who check them out, he's just not all interested.
Cinderella Circumstances: Ruby in Lock and Key comes from these; she has a poor home life that only gets worse after her mother runs off and abandons her. In something of an inversion of the actual fairy tale, Ruby is rescued from these circumstances in the first chapter and gets what most girls in her situation would give anything for - a better home, money, a new private school, and a cute neighbor who seems to take to her - but is initially resistant and uninterested to all of it.
Macy in The Truth About Forever jokes that she's like Cinderella in reverse. She spends her days as the quiet, perfect good girl then at night goes to a Wish catering job that is nonstop mess and chaos only to return home and become the good girl again by midnight.
Completely Missing the Point: In The Truth About Forever, Jason does not seem to understand when Macy explains you can't know everything that's going to happen in life. He responds to her explanation with, "But of course we'll know. We have a list."
Continuity Nod: Her books often mention characters from her previous novels.
Contrived Coincidence: Ruby from Lock and Key has an abusive mother, and then it turns out her love interest has an abusive father.
Macy from The Truth About Forever loses her father and can't find anyone who can understand her grief. She then takes a job at a catering company with five other people and all five of them have lost a loved one and understand her grief. Four of them even lost a parent.
In This Lullaby, Remy's mother has been married an absurdly high amount of times. She starts to bond with her love interest, Dexter, because his mother has been married even more times.
Control Freak: Harriet from Lock and Key, big time. It takes her forever to hire someone because she rejects all her applicants on trivial details, spends hours re-doing things she asks Ruby to do to make it "just right" and all she ever thinks about is her business.
Somewhat zigzagged with Halley in Someone Like You - she initially was very close to her mother but as she grew into a teenager and started drifting apart, her mother becomes more controlling, so Halley finds her father easier to deal with.
Ashley in That Summer. Haven is less inclined.
Mclean in What Happened to Goodbye?, mainly because she is still resentful of her mother's affair, to the point where she'd rather move around constantly with her father then live with her mother.
Dark and Troubled Past: Kristy and Monica, surprisingly. Kristy ironically handles it much better then Monica, even though she was the one who was actually in the accident, as opposed to Monica's guilt complex.
Ruby in Lock and Key. Her neglectful and sometimes abusive mother treated her horribly throughout her childhood, routinely uprooted her and moved them around constantly, forcibly kept her and her kind older sister Cora apart, and then abandoned her. Ruby lived on her own for a year, supporting herself in near poverty. She finally gets a break when she's discovered and is put into Cora's custody. Cora shares some of this past, mainly the abuse, which she usually took on behalf of the young and defenseless Ruby.
Eli. His best friend died in a car crash, and Eli was driving. The accident scarred his arms and caused him to quit bike racing.
Cora to Ruby, who would step between her sister and their mother and take the brunt of her abuse. She even does this when Jamie is yelling at Ruby for ditching school and getting drunk, Ruby looks up to see Cora standing inbetween them.
Owen seems to have shades of this towards Annabel, especially as he punches Will Cash out after Annabel confesses to him about being molested.
Drives Like Crazy: Kristy is apparently a terrible driver, but we never actually get to see this because everyone in Wish refuses to let her.
Heather in What Happened to Goodbye has a reputation for not looking before merging and gets into wrecks frequently.
Drowning My Sorrows: Ruby in Lock and Key when Cora points out that Ruby was not only abandoned by her mother, but she did everything she could to turn Ruby against her big sister, then left Ruby before Ruby could leave her.
Remy does this throughout This Lullaby but doesn't acknowledge it.
Dumb Blonde: Rachel in The Truth About Forever. She didn't understand the concept of odd numbers, according to Kristy, when Burt was tutoring her.
Early-Installment Weirdness: Although they still have her signature style, some her early novels are quite different from the formula she would develop with her later novels. Most notable are That Summer, Someone Like You, and Dreamland.
Girl Next Door: Ruby is a subversion- she lives next door to Nate, but she does not have the typical personality.
Good Girls Avoid Abortion: In Someone Like You, Scarlett is pressured to have an abortion, but she changes her mind at the last minute and keeps the baby.
Good Scars, Evil Scars: Kristy's scars are apparently very noticeable and detract from her beauty. However, they are described as being only two, somewhat faded scars and they aren't described in any way that shows them to be all that grotesque. She apparently has other, much worse scars on other parts of her body but those are usually covered up.
Hidden Depths: A part of characterization of the supporting casts (All the people in the Wish Catering Crew in Truth About Forever, especially Monica and Kristy, Maggie and Heidi in Along For the Ride etc.). Debbie in What Happened To Goodbye is a neat example where her Hidden Depths aren't a surprise to Mclean so much as to the other characters who have known her longer.
Hot Teacher: Auden's mother teaches at university and has several students drooling over her.
Huge Guy, Tiny Girl: Owen and Annabel, although Annabel isn't short by any means; she just looks so when sitting next to a guy over six feet tall.
Ill Girl: Whitney, sort of. She suffers from anorexia/bulimia and it's a major driving point behind the story.
Insistent Terminology: Emaline from The Moon and More has both her biological father and stepfather in her life; she calls her biological father "my father" and the man who raised her "my dad". It gets a bit confusing when the three of them are together.
Like Brother and Sister: Kristy's explanation for why neither she or Monica have ever gone after Wes, and similarly Kristy acts like an older sister to Bert as well.
Riley and Dave have this going on as well.
Emaline and Morris in The Moon and More. They are extremely close and devoted to one another, despite the fact that they drive each other nuts.
Living Emotional Crutch: Kristy is this for Monica, who has a lot of trouble expressing emotion and tends to shut down when she can't handle things, and Kristy jumps to defend her at every opportunity and usually explains what Monica is feeling to others who can't tell the difference.
Loners Are Freaks: The opinion of Owen Armstrong held by most of Jackson High School.
Malaproper: Kristy in The Truth About Forever; she's very fond of making up words like "tragical" and insisting they are proper words.
Man Child: Auden's father has definite shades; he is very selfish and he sulks and pouts if he doesn't get his own way, and he often pushes off responsibility for Thisbe onto Auden, despite Auden only being a teenager and supposed to be on vacation.
Meganekko: Clarke from Just Listen, Olivia from Lock and Key.
Middle Child Syndrome: Inverted in Just Listen. Whitney, the middle daughter, is causing most of the family drama and thus Annabel, the youngest daughter, is overlooked. However, part of the reason Whitney had so much drama was because she felt overlooked as the middle sister.
My Greatest Failure: Macy quits running because she was five minutes too late to save her father, who had a heart attack right before she reached him.
Red Oni, Blue Oni: Annabel's sisters fit this perfectly, with Kirsten being the red to Whitney's blue.
Also, Kirsty and Monica.
Same Story, Different Names: A criticism of her novels. The girl has an annoying, messed up family situation, girl doesn't know how to deal with it, girl meets boy, boy fixes everything in girl's hypothetical world, and then there's always that moment when Girl and Boy are going to have a falling out, but they'll be back together by the end. Not that this is necessarily a bad thing.
It got to the point, though, that when they made a movie out of her stories they went ahead and just combined two of the books.
Almost all of her protagonists fall into two categories: the quiet Type A perfectionist (Macy, Auden, Annabel, Emaline) or the cynical rebel (Remy, Ruby).
The Moon and More does make some noticeable changes to the formula, specifically Emaline not ending up with either of her romantic interests, and apparently Sarah Dessen got some flack for changing up the formula too much.
Maggie from Along for the Ride is very similar to Lissa from This Lullaby.
Kirsten and Whitney from Just Listen are very similar to Kristy and Monica from The Truth About Forever especially as they're both described as attractive blonde sisters with a rocky history. Kristen and Kristy are both outgoing, popular and have a huge Motor Mouth while Whitney and Monica are quiet loners.
All her protagonists are similar but Emaline has some major similarities to Macy.
Mclean and her novel What Happened to Goodbye? have a lot of similarities to Haven and her novel That Summer.
Mclean's mother has a lot similar to Haven's dad in That Summer (has a high profile affair, marries and starts a family with them) and Colie's mom from Keeping the Moon (goes from normal down-to-Earth mom to high-profile person with status, including going by a different name (Colie's mom went by Katherine but now goes by Kiki while Mclean's mom went by Katie and now goes by Katherine)).
Their First Time: A large part of the plot is Halley in Someone Like You dithering over whether or not to sleep with Macon. However, Scarlett's pregnancy makes her reluctant to take the risk and when she finally decides to do it, she gets cold feet at the last minute, (not to mention Macon is implied to Really Gets Around) leaving Macon very frustrated, and the ensuing argument in the car about it ends up leaving Halley hospitalised.
What the Hell, Hero?: In Lock and Key, Jamie chews Ruby out when the latter has a Heroic BSOD over Her mother abandoning her, skips school and eventually returns home drunk, even going so far as to all but outright call her an Ungrateful Bastard. Cora, meanwhile, is more sympathetic.
Owen towards Annabel after she freaks out at the club and runs away.
Where The Hell Is Springfield?: The exact location of the city where her novels take place is never revealed, it is even obscured by using made up names for universities.
Various clues throughout different novels point toward Lakeview being in North Carolina, which is also where the author lives.