The first novel by Ann Brashares, published by Delacorte Press in 2001. The book tells the story of four teenage friends and the magical Pants they share while spending their first summer apart. The Pants, ordinary-looking used blue jeans from a thrift store, somehow fit each girl perfectly, despite their widely differing body types.

Lena travels to Greece to visit her grandparents. Carmen visits her father in South Carolina. Bridget goes to soccer camp in Baja California. Tibby is the only one to stay home in Washington, D.C., working at the local Wallman's store. The Pants travel by mail, staying with one girl for a week before moving on to the next.

The story is funny in parts, relating the girls' misadventures while wearing the Pants. Their letters to each other are reproduced in four distinct styles. Each girl confronts a different aspect of love (love of a parent, love of a friend, romantic love, sex) and must decide how to react, without her lifelong friends. Although the characters are caricatures (the Jock, the Beauty, etc.) the author makes them three dimensional by showing how they are challenged and changed by their personal crises.