Rebecca Bloomwood (Isla Fisher) is a shopping addict who lives with her best friend Suze (Krysten Ritter). She works as a journalist for a gardening magazine but dreams to join the fashion magazine Alette. On the way to an interview with Alette, she buys a green scarf. Her credit card is declined, so Rebecca goes to a hot dog stand and offers to buy all the hot dogs with a check, if the seller gives her back change in cash, saying the scarf is to be a gift for her sick aunt. The hot dog vendor refuses but a man offers her $20.
When Rebecca arrives at the interview, she's told that the position has been filled by Alicia Billington. However, the receptionist tells her there is an open position with the magazine Successful Saving, explaining how getting a job at Successful Savings could eventually lead to a position at Alette magazine. Rebecca interviews with Luke Brandon (Hugh Dancy), the editor of Successful Savings and the man who just gave her the $20. She hides her scarf outside his office, but Luke's assistant comes into the office and gives it back to her. Rebecca knows the game is up and leaves.
That evening, drunk, she and Suze write letters to Alette and Successful Saving, but she mails each to the wrong magazine. Luke likes the letter she meant to send to Alette and hires her. Rather than completing a work assignment for a new column, jjjpjpjplml'mlm;mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
Rebecca goes to a clothing sale. While inspecting a cashmere coat she has just purchased, she realizes it is not 100% cashmere and she has been duped. This gives her an idea for the column, which she writes under the name "The Girl in the Green Scarf" and is an instant success.
Rebecca later returns home to renewed confrontations with her debt collector, so Suze makes her attend Shopaholics Anonymous. The group leader, Miss Korch (Wendie Malick), forces Rebecca to donate all the clothes she just bought, including a bridesmaid's dress for Suze's wedding and a dress for a TV interview. After the meeting Rebecca can't afford to buy back both and buys back the interview dress. During the interview, Rebecca is accused of not paying her debts and loses her job. Suze is angry when she finds out that Rebecca lost the bridesmaid dress. Alette offers Rebecca a position at the magazine, but Rebecca declines. She sells most of her clothes to pay her debts, including the green scarf. Meanwhile, Luke starts a new company, Brandon Communications.
Rebecca's clothes sale makes it possible for her to pay her debts. Rebecca attends Suze's wedding after reclaiming her bridesmaid dress, and Suze forgives her. Rebecca and Luke reunite, and Luke returns the green scarf after revealing that the person who bought it at an auction was acting as his agent. Rebecca becomes romantically involved with Luke and starts working at his new company.
Differences between the film and the book
- Becky is from England in the novel, but in the film she is from America. The first novel is set in London and the second in New York; the film is set predominantly in New York.
- In the books, pounds and pence are used since the book is set in the United Kingdom. In the movie, since it's set in New York City of the United States of America, they use dollars and cents.
- Becky is a brunette in the books and people can relate to her like a best friend. In the film, she is a redhead and starts of very shallow, but grows into a sensible caring person.
- In the novel, Becky's parents do not wipe out their retirement money on an RV. Instead, they tell Becky to shape up and save her money by cutting back on her spending sprees or make more money.
- In the novels, Suze and Tarquin are cousins who gradually proceed to date, and Becky is the only bridesmaid. In the film, Suze and Tarquin are dating seriously, appearing in the same bed together and there are multiple bridesmaids.
- In the novels, Luke proposes to Becky at Suze and Tarquin's wedding.
- In the novels, the Denny and George scarf is described as being blue and gray, but the movie prominently features Becky as The Girl With the Green Scarf.
- Luke and Becky never went to Miami in the novel. They went to New York in the 2nd Novel.
- In the novel, we start off with Becky already working at the Successful Saving magazine, but in the film adaptation, she works for a gardening magazine and goes in for an interview at Successful Saving after arriving too late for an interview at Alette.
- In the novels, Clare Edwards is described as boring and smug, whom Becky doesn't really like because of it. The only time she showed compassion towards her was near the end of the 2nd novel before they both were set to go on the air. In the film adaptation, Clare is more passionate and polite in trying to help Becky out of her debts as she too has know what it was like herself.
- In the 1st novel, Philip is Becky's boss (at Successful Saving) and Luke owns his own PR firm, Brandon Communications. In the movie, however, Luke is Becky's boss and omitted Phillip from it.
- The novels also introduces Alicia Billington as a senior employee of Brandon Communications and Becky commonly refers her as Alicia Bitch Long-Legs due to both her taller height and her apathetic nature towards others. She and Suze have a bitter history with each other. In the film, her character is a rival got a job (that Becky had wanted) at Allete, a fashion magazine.
- The film omits characters from the novel, such as Martin and Janice Webster (as well as their son, Tom and his girlfriend Lucy), the Bloomwoods' next door neighbors and close friends as well as Luke's then-girlfriend, Sacha de Bonneville and Becky's other friend, Elly Granger.
- In the novels, Becky went to the TV program Morning Coffee because of an article that she wrote on the Daily World about a terrible thing Luke's client, Flagstaff Life, did to her neighbors in cheating them out of good money. Luke was furious at what she did and argued with her for a while, thinking she was getting back at him for humiliating her at Harrods. Soon, Luke admits Becky is right and announces that his company won't continue being a client of the bank who defrauded their customers. In the film, she went to the program with Luke to talk about The Girl With the Green Scarf.
- Also omitted are certain minor story lines from the novels, such as Suze's frame making business aaong with Becky's involvement with both her neighbor's pension issues and helping Luke buy an expensive suitcase for his then-girlfriend, Sacha. Becky has also tried to date Suze's cousin, Tarquin, but eventually gives up as he isn't her type and begins dating Luke after Sacha dumps him.
- In the novels, Endwich Bank manager Derek Smeath is polite and professional, but very persistent as Becky turns him down on every contact. In the end, they agree to work out a settlement with her card when she realizes it's time for her to grow up. In the 2nd novel, Smeath's successor, John Gavin, is much more vicious and refuses to help Becky out when she asks for a bigger overdraft. In the film adaptation, Smeath begins as a mild-mannered, polite and professional bank manager. He slowly becomes more vicious as Becky tries to avoid a meeting with him concerning her credit card debts. Desperate, he accepts the help of Alicia Billington and humiliates Becky in public on her TV début. In the end after Becky pays off her debts, she pays him back by leaving a couple of jars in pennies worth thousands of dollars for him to count on his desk.
- In the second novel, Alicia intentionally ruins Becky's TV career by exposing her in an article from Daily World calling her a fraud for telling people how to save money when she can't save her own money. As a result, she loses her job at the Morning Coffee and is replaced by former co-worker Clare Edwards. When Becky overhears Alicia telling a few colleagues about her plans to run Brandon Communications out of business by stealing their most trusted clients, including the Bank of London, so they can set up business elsewhere with her fiancé, Ben Bridges, she decides to learn more about it. After doing some detective work, she exposes Alicia's plans to Michael Ellis and also asks not to tell anyone it was her. The next day, Luke immediately returns to London to search for evidence and finds plenty against her, including bank statements belonging to Becky. Furious, he fires Alicia along with her colleagues for intentionally trying to ruining his company's integrity with their clients. In the film adaptation, she helps Smeath ruin her rival's TV debut by exposing her in public. Alicia was fearful and jealous that Allete Naylor is more interested in hiring the fashion-oriented Becky after a trip at an expensive clothing store which she helpfully accessorize for her with the latest fashion trends. In the end like her novel counterpart, Alicia is fired from Allete by her boss for her scheme to ruin and humilate Becky publicly.
- In the novels, Becky doesn't accept a job at Brandon Communications and instead is a personal shopper at Barneys New York, in Manhattan. She makes a couple of TV appearances on the fashion trends and how to accessorize them, while in the movie she helps Luke run Brandon Communications.
- In the 2nd novel, Suze advises Becky to merely get rid of some of her unnecessary items from her closet. She has a better idea: auctioning off her clothes, including her Denny and George Scarf. This turns out to be a success and Becky made more than twice her money back to pay off her debts. While in the film adaptaion, Becky goes to her support group for advice and Miss Korch tells her to sell off her unecessary possessions.
- In the movie, Becky explains in a voice-over for the closing credits that she went to a meeting to deal with her addiction for shopping and is now a reformed shopaholic. In the novel, she tried cutting back or making more money.
- In the first novel, Becky worked for a clothing store in an attempt to make more money to pay off her credit card debts. However, she was immediately fired on her first day for hiding a pair of fashionable pants from a customer interested in buying them because she wanted the pants for herself.
- In the novels, Suze is a blonde and is from a wealthy, aristocratic family. In the film, she's a brunette and there's no mention of her family being wealthy.
- In the film, Suze was upset with Becky when she learned that Becky gave away an expensive bridesmaid dress to the wedding, while in the third novel, Becky's dress was made by her designer friend, Danny Kovitz, whom she helped become a famous fashion designer.
- The first novel has already introduced Luke as the CEO of Brandon Communications, while in the movie he was boss of Successful Saving before leaving to form his own PR company