For anyone who hasn't been perusing bestseller lists, or hasn't visited a bookstore and seen an eye-catching pair of faded blue jeans on a book jacket, hearing someone mention "that pants book" might engender only confusion. But the many thousands of teenagers who have discovered the book and are passing it around to their friends would know instantly what you were referring to: The Sisterhood of the Traveling Pants, written by Ann Brashares (Delacorte).

The idea for the book, in which four teenage friends spend their first summer apart but share a pair of secondhand jeans, stemmed from when Brashares was a partner at 17th Street Productions, a book packager specializing in middle grade and young adult books. As Brashares recalls, "I was talking with Jodi Anderson, an editor at 17th Street, and she was telling me how she and a friend had shared a pair of pants over one summer. That immediately sparked a bunch of ideas. I said to her that it should be a novel, that it was such a fun idea."

She took the idea to Random House, where she worked on it with Beverly Horowitz and Wendy Loggia. "Jodi was very instrumental in helping me developing the premise," Brashares says. "I'm incredibly grateful to her for letting me use a small part of her life. From the first manuscript, Jodi, then Beverly and Wendy had a lot of good ideas for revisions--not structural stuff, but line-by-line stuff."

In writing for teenagers, Brashares says, "you feel such a sense of responsibility. You want to tackle certain issues. But I didn't feel like it was an 'issues' book--I wanted it to be fun, and a pleasure. And I want the stories I write to elicit an emotional response, to get readers thinking and feeling about my characters."

The book was completed, advance copies were handed out at BEA and a publication date was set: September 11. "All summer I had that date in mind," she recalls. "But then everyone's priorities shifted." The morning of the 11th she was on her way to her local Barnes & Noble in Park Slope, Brooklyn, when she heard about the attacks on the World Trade Center, just a few miles away. "I ran home, and it wasn't until much later that night that I realized, 'Oh God, this was supposed to be my publication day. I remember thinking, 'Well, that'll be important again one day, but not right now.' "

The unfortunately timed pub date, however, didn't seem to hurt the book: it now has 160,000 copies in print after eight trips to press, and Warner Bros. has purchased the film rights. Brashares says the book's success "is giving me the confidence that I can be a writer, that it can be my job and my life." She recalls her excitement when the buzz about the book began, thanks to those BEA readers' copies. "As a writer, you live in such isolation. It's hard to imagine your book has a life beyond you. Each piece of feedback was such fun! And there is the sheer joy of a first book, that somehow your thoughts translate into other people's worlds."

Brashares, who shares a brownstone with her husband and their three children (all under the age of six), says she writes at home, usually in the morning. "But I tend to try to run back downstairs to the computer at night, after the kids go to sleep." Currently she is at work on a sequel to Pants. "It will involve the same characters," she says, "but they're a little bit older."

And she hopes to do other kinds of writing as well. "I'd love to try to write an adult novel, also a book for a younger age group. But for now, I've very happy writing for young adults. Hopefully, life will be long, and I'll get to try other things."