In the first novel of the series, the reader is introduced to four high school students: Lena Kaligaris, Tibby Rollins, Bridget Vreeland, and Carmen Lowell.

The summer before their junior year of high school, Carmen finds a pair of old jeans that mysteriously fits each girl perfectly, despite their different sizes.

Bridget pursues him in spite of the camp's prohibition on coaches and campers entering relationships with each other, and eventually sees him in his underwear.

Ann Brashares got the idea for the novel while working as an editor when, colleague Jodi Anderson proposed the concept of a group of girlfriends who share a pair of jeans.

In the novel, the family is portrayed as being rooted in one's birth yet dynamic, and also as existing between friendships in addition to blood relatives.

The girls are expected to make decisions for themselves and behave as responsible adults, as well as to figure out how to overcome obstacles and take risks.

USA Today's Deidre Donahue said Sisterhood "has resonated far more deeply than any of the grown-up novels I've read this year.

"[3] Linda Bindner of the School Library Journal called it "a complex book about a solid group of friends, with each one a strong and courageous individual in her own right."

Publishers Weekly described it as "an outstanding and vivid book that will stay with readers for a long time.