Alastair Heim is the author of more than 20 children’s picture books including the #1 New York Times bestselling How the Grinch Lost Christmas!, as well as Hello Door, which was named one of The New York Public Library’s Best Books, The Great Puppy Invasion, which won the Oklahoma Redbud Read-Aloud Award, and Quiet Down Loud Town!, which was named a Junior Library Guild Gold Standard Selection. He has also written four books for Dr. Seuss Beginner Books titled If I Had Your Vote, If I Ran Your School, If I Were Saint Nick and If I Drove an Ice Cream Truck, all featuring The Cat in the Hat. He lives in Kansas City with his wife and children.

New Jersey native and "constant doodler" Aristides ("Art") Ruiz has illustrated over 100 books for children—among them more than forty books in the Cat in the Hat's Learning Library series. He is the illustrator of the #1 New York Times bestselling How the Grinch Lost Christmas. A versatile artist, he divides his time between illustrating for children and fine art painting.