Party Princess is a novel in the Princess Diaries' series by author Meg Cabot. The story follows the main character, Amelia "Mia" Thermopolis as she tries to balance her high school problems with having a boyfriend in college.

Mia struggles with juggling her duties as a royal, such as her princess lessons with Grandmere, with her role in student government where she has to raise money to pay for the senior class commencement ceremony. Additionally, Mia is dealing with having her boyfriend, Michael, attend his first year of college while they continue their relationship. Specifically, Mia thinks that Michael wants her to be more mature and more of a party girl, similar to the girls that he knows in college. When Michael decides to have a party at his parents' apartment, Mia decides that she should dress and act like a party girl.

While Mia is trying to figure out how to raise the five thousand dollars she needs to rent the hall for the commencement ceremony, Grandmere decides to force Mia to star in a musical that Grandmere has written. Grandmere wants the musical performance to occur at a benefit that she is hosting for the olive farmers of Genovia. Grandmere's motive in hosting the performance is not altruistic however. Instead, she desires to win the bid on an island off Dubai that is in the shape of Genovia. In the end, Grandemere gets her island and Mia is able to raise the money that she needs for the commencement ceremony, but in the process, she learns that she can accomplish her goals by telling the truth rather than being manipulative.