Caitlin is a girl with short blonde hair who works at the Big Squeeze and is the only child of wealthy parents. Pretty, perky and generally sweet-natured, she loves shopping, wearing pink outfits (including her trademark sleeveless pink top), listening to boy bands and pursuing boys for romantic relationships, though her dates usually end in disaster for various reasons. Caitlin first got her job at the Big Squeeze in the series pilot after her father recommended she seek employment to pay off her credit card debt, and she quickly became friends with the other main characters.
Caitlin was once friends with Tricia, a snobby shopping buddy of hers, but Tricia ended the friendship after Caitlin began working at the Big Squeeze, considering working for a living to be "beneath" her. Since then, Tricia (with the help of new friends Mandy and Gwen, who are equally as stuck-up as Tricia is) has endeavored to make Caitlin's life miserable by always one-upping her ex-friend and sabotaging her plans at every opportunity, but Caitlin usually manages to get the upper hand over her friend-turned-rival with help from Jonesy, Jen, Nikki, Jude and Wyatt.
Personality-wise, Caitlin is the most emotionally sensitive character out of the main cast. She is usually happy, bubbly and upbeat, traits which draw the occasional putdown quips from the more cynical Nikki (particularly when they have disagreements from time to time), and she has a trusting nature which has made her vulnerable to being taken advantage of by Tricia or other unscrupulous characters before Cait's friends helped her learn to become more street-smart. She is also prone on occasion, and more so in later episodes, to mood swings (including irrationality and a short temper), distraction, fits of jealousy and a competitive streak which sometimes hurt her friends, which Caitlin usually regrets afterward as she does what she can to make amends to them. On several occasions in later seasons, she has proven to be incapable of keeping the secrets of her friends, as any secret any of the gang tells to Caitlin (voluntarily or otherwise) invariably gets blabbed by Caitlin to the rest of the gang, and sometimes even to other people, much to the embarrassment and frustration of her friends as they subsequently reprimand Caitlin for betraying their trust in her.
Caitlin has also been known to easily cry when things go seriously wrong for her or her plans otherwise don't go for her as she would like; the causes for this range from the trivial (like a bad hair day) to the serious (like being dumped by a boyfriend, or when Tricia tries to make trouble for her), but she knows that the gang is there to support and comfort her when she is down. In return for helping make her a better and more well-rounded person, Caitlin often helps out her friends by giving dating and relationship advice, fashion makeovers, and supporting them in other ways.
Caitlin gets her first job as an employee at the Big Squeeze after her credit card reaches its limit and she has to pay off her debt ("Take This Job and Squeeze It"), and she receives training for the job from previous employee Jen, who is moving on to the Penalty Box—and while she loses Tricia's friendship, Caitlin later saves Jen's Penalty Box job when, as Coach Halder is about to fire Jen before she even gets started, Caitlin pleads Jen's case and begs him to give her a chance. She later wins over Nikki, who was initially unfriendly toward her, when she uses her acting skills to convince Jen to take a sick day off work and join the gang at The Galleria's indoor amusement park ("The Big Sickie"). Caitlin comes close to getting her job transferred to a strip mall across town due to poor sales and Jonesy setting up a rival drink stand at the food court ("A Lime to Party"), but she saves her job at the Big Squeeze when she improves her work ethic and the drinks she makes, combined with Jonesy helping out by getting himself fired. With help from Jen, she lands a date with Kyle Donaldson, who turns out to be a womanizer ("The Sushi Connection"), and the date ends in disaster for Cait when she eats sushi (a food she hates) and later gets sick and vomits on Kyle on a roller coaster ride at the amusement park.
Caitlin helps Jen try to get the attention of new Penalty Box employee Charlie Dobbs by setting her up with a "fake date" in Jude for the PB staff party ("The Fake Date"), which doesn't go well when Jen ignores Jude in favor of Charlie and Jude gets wired on energy drinks. Caitlin and Jen discover that Nikki is secretly a fan of boy band DawgToy ("The Girls in the Band"), and Cait later gets to meet her favorite DawgToy member, John, in person after Nikki, who won an audition to be in the band's latest video earlier, arranges to have her and Jen meet the band. When Jonesy and Nikki become drawn to each other romantically, Caitlin, worried that the gang would be forced to choose sides if the two of them broke up, teams up with Jen and Wyatt to keep them apart ("Clonesy"). When Wyatt cancels his Valentine's Day plans after a misunderstanding when he overhears Serena talk about what she thinks of the holiday ("Stupid Over Cupid"), Caitlin and Jen convince him to reconsider and take Serena out on a date. Caitlin vies with Tricia for the title of "Khaki Girl" and a shopping spree in a contest at the Khaki Barn ("The Khaki Girl") and, after outdoing Tricia in every event in the contest, originally loses when when her friend-turned-rival cheats, but she becomes the Khaki Girl anyway when Tricia, in an act of karma, becomes ill with food poisoning.
Caitlin tries getting a job as a Greeter Goddess at Albatross & Finch but loses out to Jonesy ("The (Almost) Graduate") and later gets saved by Jonesy when he gets himself fired for mooning the A&F staff after he catches two snobby Greeter Goddesses harassing Caitlin, while she helps Wyatt learn to be more mature in preparation for a date with Serena. After having poor luck in past dates with boys, she gets advice from Jude, masquerading as a swami, and lands a date with her new crush, Jeff ("The Swami"), but her overreliance on Jude's advice causes problems on the date. Caitlin, with Jen and Nikki, takes part in a "Battle of the Sexes" against Jonesy, Jude and Wyatt ("Bring It On"), which the girls end up winning when the guys run into problems dealing with several bratty kids they mind at the mall daycare and are forced to ask for the girls' help. She joins with Jonesy and Jude in playing a prank on Nikki, which Jonesy films for public access TV ("Cecil B. Delusioned"), by pretending to have broken up with a boyfriend and convincing Nikki to get a fashion makeover. When Caitlin and her friends' busy schedules prevent them from planning a 16th birthday celebration for Wyatt until it's too late when most of the mall's stores close ("The Birthday Boy"), the gang improvises by hijacking a bridal shower at Albatross & Finch and taking Wyatt there, making him believe that they actually threw a party for him.
The effects of her menstrual cycle cause Caitlin to go through mood swings as she starts acting grouchy ("Enter the Dragon"), and she discovers that her cycle has synced up with those of Jen and Nikki, creating a bond between the girls. She meets Jen's sister Courtney ("It's Always Courtney, Courtney, Courtney!"), whom Cait finds a bond with when the two of them go shopping together, much to Jen's chagrin. Caitlin finds a dress that she wants to buy for a homecoming dance but is unable to afford ("The One with the Text Message"), and she develops a rivalry with Jen over the dress after Jen decides to buy it for herself, but the two girls later make up after Jen changes her mind about the dress and trades it to Caitlin for another dress she buys, and after Jen comes down with stomach cramps from unknowingly eating mushrooms, Cait reluctantly stays with Jen in the women's washroom after she confesses to Nikki that she allowed Jen to eat the mushroom-laced food item, knowing what they would do to her, as revenge for Jen's claim on the prized dress. Caitlin scores a date with new crush Talon for a Halloween monster movie festival at the Gigantoplex and gets a Las Vegas showgirl costume for the event ("Boo, Dude"), and she is accidentally victimized by a Halloween prank intended by Jonesy for Ron the Rent-a-cop.
Caitlin worries about her relationship with Talon after she accidentally injures him several times ("Going Underground"), but she ultimately breaks up with him after Talon turns out to be a bad kisser. She believes that she will become a travel writer after Jude mixes up her high school aptitude test with Nikki's ("Career Day"), and Nikki despairs when she mistakenly gets Cait's test and thinks she is doomed to being a "retail specialist". Caitlin and Nikki have a falling out after Nikki has enough of Caitlin talking nonstop about her latest boyfriend Wade ("Fish and Make Up"), but the two girls later make up after Jude's new pet, a goldfish called Fish, dies and they console a despondent Jude. She helps co-ordinate Jonesy and Nikki's three-month anniversary celebration, which regrettably ends with the couple breaking up ("Unhappy Anniversary"), and her own relationship with new boyfriend Zane draws the attention of Zane's ex, Tricia, who vindictively causes trouble for Caitlin by getting her banned from every store in the mall and labels her a "boyfriend stealer", causing Caitlin and Tricia to fight at the mall fountain and resulting in Zane dumping Cait.
Caitlin betrays the trust of her friends when she spills their secrets to new boyfriend Dustin (while conveniently leaving out her own secret) and he subsequently blabs those secrets to everyone in the mall while under hypnosis at a stage show ("Pillow Talk"), so the gang evens the score by recruiting Tricia to tell Dustin Caitlin's secret; she loses another boyfriend when Dustin dumps her, but she apologizes to the gang afterward. She finally pays off her credit card debt and quits the Big Squeeze ("Losing Your Lemon"), handing her job over to new employee Katie—and Tricia rekindles her friendship with Caitlin and takes her shopping while simultaneously causing problems for Cait's friends by bringing a group of doppelgangers of each of the gang in to take Jonesy and company's table by the Big Squeeze, until Caitlin comes to her senses, convinces Katie to leave the Big Squeeze for a new job at the mall information kiosk, then takes back her job at the lemonade stand and kicks Tricia and the doppelgangers out to the gang's delight. She helps Nikki give Darth a makeover and they set him up with nerdy Wonder Taco employee Julie in order to get Darth to leave Nikki, his unrequited crush, alone ("Welcome to the Darth Side"), and she later helps Ron, who feels depressed and desolate after being forced into early retirement by a prank played by Jonesy and Jude ("The New Guy"), look for new employment and ultimately get his security guard job back.
Caitlin gets a side job as a personal Christmas shopper ("In a Retail Wonderland..."), but she loses the will to shop when she becomes depressed after another boyfriend dumps her, then gets it back with help from Nikki, whom Cait then convinces to go with her parents on a trip to Mexico for the holidays. She meets a new guy who agrees to go out with her, on condition that she also find a date for his slovenly best friend Carl ("Lords of Mall Town"), so she convinces a reluctant Jen to be Carl's date. Caitlin ends up getting a bad mullet hairstyle after "cheating" on her regular stylist to get her hair done by world-famous stylist Fabris during a demonstration at the mall centre court ("Major Unfaithfulness"), and the resulting misunderstanding when she tries to hide her bad hair day almost leads to a breakup with her boyfriend Joe, who she fears will dump her because of her bad haircut, until they clear things up--and Cait later dumps Joe after he gets a Mohawk haircut, then she refuses to see the hypocrisy in her actions following her own bad hair experience when the gang points it out to her. She meets a boy named Tad while waiting in line for a sale at Albatross & Finch ("Waiting to Ex-Sale"), and they go through all the stages of a relationship in the space of a few hours before Tad breaks up with her after an argument, but Jen helps Caitlin get over the breakup. She tries setting Nikki up on a date with A&F Greeter God Hunter, but that plan backfires when Hunter instead asks Caitlin out on a date ("The Hunted") and Nikki gets angry with her when she finds out, but Nikki and Cait make up after they find out about Hunter's womanizing ways and they get their revenge on him at the food court. She gives Jude a goth makeover in order to help him understand his girlfriend Starr's recent turn to the goth lifestyle and stay together with her ("Lights Out"), which turns out in vain when Starr (who now calls herself "Nebula") breaks up with Jude. After learning that Nikki is dating a like-minded new guy named Stone ("Jonesy's Low Mojo"), Caitlin and Jen team up to covertly follow Nikki on her date with Stone to ensure that she is okay.
Caitlin meets a college guy named Josh, who is led to believe that she is also attending college ("Smarten Up"), so she buys herself a college-style outfit of jeans, a tweed blazer and glasses and she convinces Jen and Nikki to help her play the part when she goes on a date with Josh, then later pulls the entire gang into the act. She buys a new bronzing makeup called "Smashface", which causes her face to break out in zits when she uses it ("Dirty Work"), forcing Nikki to make Caitlin (who is reluctant to give up the makeup despite the undesirable reaction it has on her skin) throw the makeup away, leading to her face returning to normal afterward. Caitlin is framed for shoplifting from Albatross & Finch by Tricia, who tricks her ex-friend into going shopping with her to set her up after she overheard Cait criticizing Tricia's selfish behavior to Jen earlier ("A Crime of Fashion"), but she gets her name cleared with help from Nikki and Darth after obtaining the security tape exposing Tricia, who is then arrested for shoplifting and sentenced to community service for punishment. She appoints herself as Nikki's image consultant when Nikki decides to run for Spring Queen against Tricia ("Spring Fling"), she lands a job at the Chocoholics Anonymous candy store and ends up gaining weight after sampling some of the store's chocolate ("Girly Boys"), and her attempts to ask Steph, a new boy she likes, to the school winter dance backfire and get her branded a stalker by Steph ("Snow Job"), but she gets over it and joins her friends at the dance.
Caitlin makes plans for her 16th birthday with a birthday bash which she invites her friends and her new crush Benj to ("Sweet 6teen"), but Tricia, who wants Benj for herself, sabotages Caitlin's plans by convincing her to hold a joint Sweet 16 party, then stealing her party, her ideas and Benj from her; the gang comes to Cait's rescue by planning their own party for her, and Tricia's divaesque behavior (and some counter-sabotage by Nikki) spoils her party and makes Benj walk out on her to return to Caitlin. She becomes obsessed with a "Babymaker" photo booth which, no matter what guy she pairs with, produces photos of ugly babies while similar photos produced from other couples (including, on a lark, Jen and Jude) turn out to have beautiful babies ("Baby, You Stink"), and she acts as one of the judges (along with Jen and Nikki) in the guys' "Man-Off" competition to determine who, between Jonesy, Jude and Wyatt, smells the least after a week of not showering. Caitlin lands another new boyfriend named Les ("Selling Out to the Burger Man"), with whom the only thing she has in common is shopping (as he is a shy boy with average looks and personality), and Jen and Nikki are forced to intervene when Les nearly goes broke buying clothing items that Cait likes so he can hang onto her. She reveals the private thoughts in Jen's journal, which had been thought lost, to everyone in the mall when she looks through it on her way to bringing it back to Jen ("The Journal"), but after Jen gets angry at her friends for spying in the journal, Caitlin (who was primarily at fault for publicly reading the journal aloud in the first place) helps the gang make it up to Jen afterward and win back her trust.
Caitlin makes Jude tell her the secret he has ("Silent Butt Deadly"), which is that he has a secret girlfriend in high school senior Melinda Wilson, and then tells the secret to the rest of the gang, to Jude's chagrin. After cashing her paycheck and getting more money in a withdrawal than she asked for from a haywire ATM ("Prank'd") and then hearing of a contest her bank is holding, she mistakenly believes that she has won the contest's grand prize and goes shopping with the cash—but she then regrets it when Tricia takes notice of Caitlin's accidental windfall and wants to become friends again. Cait assists Jonesy when he gets hired by Coach Halder to hold wrestling matches at the Penalty Box to aid in the sales of wrestling equipment ("Wrestlemania"), massaging what Jonesy believes at first is a muscle-relaxing cream into his shoulders in between matches (but which she later tells him is really a nerd repellent called "Creep-Off"). She ends up in a dating dilemma when she falls for two handsome guys, Vince and Blake ("2-4-1"), and she tries dating both because she is unable to decide which one to pick for a boyfriend. She mistakenly believes that Jonesy has a crush on her as the result of the gang's new cell phones, which she has obtained for them through her father's company, malfunctioning ("Oops, I Dialed It Again").
Caitlin, along with the rest of the gang, becomes concerned when Ron gets out of control with his security duties, abuses his power and harasses anyone celebrating the Christmas holidays at the mall ("How the Rent-a-cop Stole Christmas"), climaxing with Ron arresting the entire gang on trumped-up charges—until Caitlin and company discover the reason the Galleria head of security is getting carried away with his job is because he has no one to celebrate the holidays with, so they join Ron for a get-together at the security office. She helps Wyatt try to get over his lingering feelings for Serena after he commits a few blunders that get him in trouble with Marlowe ("Insert Name Here") by doing a "Serena purge" to rid himself of all things that remind him of his ex-girlfriend. She becomes involved with a boy who is into animal rights after he sees her holding Tricia's pet dog ("All Pets Are Off"), and after Jonesy gives her a ferret from the discount section of the pet store he is working at, Caitlin starts acting uncharacteristically as she begins insistently calling the ferret a "purse dog" and irrationally gets angry at anyone who corrects her by calling the animal by its proper name. After noticing that Jen has transformed herself into a clone of her temporary boss at the Penalty Box, Jane ("J Is for Genius"), Caitlin remarks that Jen has developed a "girl crush" on Jane (which Jen promptly denies), then adds that if there is anyone whom Jen should be patterning herself after, it would be Cait herself. She finds out that she has a male coworker at the Big Squeeze whom she has never met, named Kevin ("Bicker Me Not") and she sets out to meet him by trading notes with him during their respective shifts; she is smitten when she finally meets Kevin, but to her embarrassment, he explains that he thought Cait was a guy and that they do not have the same interests before leaving, with Gracie Bickerson explaining to Caitlin afterward that Kevin is homosexual.
An embarrassed Caitlin has developed a cold sore after catching it from a boy she was dating ("The One with the Cold Sore") and temporarily swears off guys as a result, but she spends the day with Jude and ends up passing the cold sore to him by sharing a snow cone with him, while the rest of the gang mistakenly assume that she and Jude have started dating; as with the time she had the ferret for a pet, she makes up a name for the cold sore (calling it a "lip thingy") and vehemently stands by that name despite the gang's efforts to correct her with the proper term for her condition. Caitlin, along with Jen, Tricia and The Clones, discover that they are simultaneously dating a Greeter God from Albatross and Finch ("Double Date") and they set out to get revenge against all guys at the mall, but when Tricia decides to target Jude and Jonesy as part of her sudden feminist kick, Caitlin and Jen realize that this is really Tricia's latest scheme to cause trouble for Cait by trying to turn the gang, Caitlin's main support network for dealing with Tricia, against each other. After discovering that her latest crush, Sawyer, is a "breast man", she sets out to do some breast enhancing of her own by buying a water bra from Jonesy, who has begun selling them as his latest job ("Whoa, Baby!"), but ends up humiliating herself when her overfilled bra springs a leak and soaks Sawyer. She hooks up with a boy named Jasper, whom she assumes is Spanish, and has to learn to speak Spanish herself to talk to him ("Cheapskates"), not realizing that the boy she heard speaking the language, sight unseen to her, was actually Jasper's friend. She gets competitive with Jonesy and Nikki over setting Jen up with a date for an upcoming wedding the gang has been invited to ("Mr. and Mr. Perfect"), and after saving Darth from a bully ("Lifeslaver"), the Star Wars geek, acting according to his Jedi Code, becomes indebted to protect her in return, prompting Caitlin to stage some "near-death" experiences to get Darth to pay his debt and leave her alone, and incurring the wrath of Darth's girlfriend Julie in doing so.
While at the hospital with the rest of the gang to accompany Jen's mother during her pending delivery of her new daughter Emma, Caitlin runs afoul of a hospital rule forbidding the use of cell phones inside the hospital when she continually defies the rule and gets her phone taken away by a maternity ward doctor as a result ("Labour Day (1)"), and she later takes offence to a new cell phone prohibition sign with her picture on it and she rudely interrupts Jonesy three times while he tries to talk to her after she asks what he was up to earlier ("Labour Day (2)"). She is entrusted with the care of baby Emma by Nikki (who is proxy-watching her on Jen's behalf) when Nikki unintentionally tells an embarrassing secret to Caitlin, who betrays her trust by blabbing the secret to the rest of the gang and to Darth ("6 Teens and a Baby") after she gets vomited on by a nauseous Emma. After she gets dumped by her newest boyfriend Spencer, Caitlin again swears off guys and develops a new, nasty anti-boy attitude (and makes Jude an unwarranted and undeserving first recipient of her newfound bitchiness), which she then parlays into a career as a budding artist who paints portraits of all the boys she has dated and then destroys the finished canvas before putting them on display ("Blast from the Past"), but when her new irrational attitude gets out of control, Nikki and the rest of the gang are forced to stage an intervention on Caitlin and convince her to return to her normal upbeat and pleasant self. She gets an opportunity to meet and hang out with teen singer Kylie Smylie after winning an essay contest ("Kylie Smylie"), and she attempts to play matchmaker for Kylie and Wyatt while keeping Wyatt under the radar of Kylie's overprotective father/manager, an ex-pro wrestler called Sgt. Beef.
- Until Season Three, Caitlin was assumed to be 16 years old along with her friends, but she celebrated her 16th birthday in the Season Three premiere "Sweet 6teen", thereby retroactively making her 15 years of age during the first two seasons
- Caitlin is susceptible to Premenstrual syndrome, whose effects cause her to become moody and grouchy (as seen in "Enter the Dragon"). Drinking a specific kind of herbal tea neutralizes the mood swings and restores Caitlin to her normal bubbly self
- Caitlin's cell phone ringtone is set to the tune of the Britney Spears song "Oops I Did It Again"
- Her name in the French-language version of the series is Katherine (Kathy) Cloutier
- In 6teen's pre-development incarnation as The Mall, Caitlin sported longer, shoulder-length hair and her pink top had short sleeves, as well as her general appearance looking different from the eventual result in the series as aired