Kunhardt wrote nearly 50 books, including one of the bestselling children's books in history, "Pat the Bunny," which has sold over six million copies. She initially wrote it for her youngest child Edith. Other works include "Twenty Days," an account of Lincoln's assassination and the twenty days that followed, which she wrote with her son, Philip B. Kunhardt, Jr.; "Tiny Animal Stories"; "The Telephone Book"; "Lucky Mrs. Ticklefeather"; "Brave Mr. Buckingham"; "Junket is Nice" (1933); "Wise Old Aard-Vark" (1936); and "Now Open the Box".