Carmen Lowell is working on the backstage of a play in Yale. When the lead actress and friend Julia invites her to travel to Vermont with her to work in a play with professional cast... Carmen Lowell is working on the backstage of a play in Yale. When the lead actress and friend Julia invites her to travel to Vermont with her to work in a play with professional cast, she decides to stay with her friends and her pregnant mother. However she finds that Lena Kaligaris will travel to a course of drawing. Bridget Vreeland is in existential crisis missing her mother and decides to travel to an archaeological dig in Turkey. Tibby Tomko-Rollins is working in a rental and still editing her documentary. Therefore, Carmen accepts the invitation and travels to Vermont. She has a crush on the lead actor Ian, who convinces her to participate in an audition, and is invited by the director Bill Kerr to perform the lead female role. Later she finds the truth about the friendship of Julia. The broken-hearted Lena finds that Kostas has just married and she dates the model of her class. Bridget finds letters addressed to her from her grandmother that her father has hidden and she decides to visit her grandma, disclosing a secret about her mother. Tibby makes love with her boy-friend Brian McBrian but they have problems with the condom and she gets scared of a possible pregnancy. In the end, the girlfriends discover that their friendship is real and more than a pair of jeans.

The movie is based on the young adult book, The Sisterhood of the Traveling Pants, by Anne Brashares. As four best friends spend their first summer apart from one another, they share a magical pair of jeans. Despite being of various shapes and sizes, each one of them fits perfectly into the pants. To keep in touch they pass these pants to each other as well as the adventures they are going through while apart.