Kate McMullan is the author of many books for young readers, including How Do You Take a Bath? with Sydney Hanson; I Stink!, winner of the Boston Globe-Horn Book Honor, and I'm Mighty! with her husband, noted illustrator Jim McMullan; and Meg's Prairie Diary, a historical fiction trilogy set in St. Louis and Kansas in 1856.

She has been fascinated by the Lewis and Clark Expedition since the age of ten, when an uncle told her about an ancestor who had gone on the expedition. That ancestor was sixteen-year-old George Shannon. Kate lives in New York City and Sag Harbor, New York, with her husband.