"One! Hundred! Demons!" first appeared as a serialized comic on Salon.com; according to the book's introduction, it was produced in emulation of an old Zen painting exercise called "one hundred demons." In this exercise, the practitioner awaits the arrival of demons and then paints them as they arise in the mind. The demons Barry wrestles with in this book include regret, abusive relationships, self-consciousness, the prohibition against feeling hate, and her response to the results of the 2000 U.S. presidential election. The book contains an instructional section that encourages readers to take up the brush and follow her example. According to "Time" magazine, the book uses "acutely-observed humor to explore the pain of growing up."