Mac Barnett is the author of numerous books for children, including five illustrated by Jon Klassen: Square; The Wolf, the Duck, and the Mouse, an E. B. White Read-Aloud Award winner; Triangle; Sam and Dave Dig a Hole, an E. B. White Read-Aloud Award winner and a Caldecott Honor Book; and Extra Yarn, which received a Caldecott Honor and a Boston Globe—Horn Book Award. Mac Barnett lives in California.