New Jersey native and "constant scribbler" Aristides ("Art") Ruiz has illustrated 100+ books with over 60 Dr. Seuss titles including projects for GREEN EGGS & HAM, HORTON, THE GRINCH, and THE CAT IN THE HAT.

He is the illustrator of The Cat in the Hat's Learning Library books since 1998 with 40+ titles (and counting) thus far in the series.

A versatile artist, he divides his time between illustrating for Seuss and fine art painting because... well,.. he's a scribbler. He's constantly scribbling...like a lot.

Bonnie Worth is one of the pen names of Kate Klimo. For many years, Kate was Vice President and Publisher of Random House Children’s Books, the one and only home of Dr. Seuss, aka Theodor Geisel. In addition to being a Random House best-selling author, he was also publisher and founder of Beginner Books, an imprint that boasts such Seuss-penned classics as The Cat in the Hat, Hop on Pop, and Green Eggs and Ham. One of the last projects Geisel worked on, in conjunction with NASA, was a non-fiction Beginner Book spin-off. Unfortunately, he died before he was able to launch the series. In her capacity as publisher, Kate picked up where Seuss left off.

With the 1999 publication of Oh, Say Can You Say Dinosaur? Kate launched The Cat in the Hat’s Learning Library. Today, the series numbers more than two-dozen best-selling titles, half of which were written by Bonnie Worth. One of her last acts before stepping down as publisher from Random House, was to work with PBSKids to develop an animated television show with a natural science curriculum, based on the Learning Library. Now in its third season, The Cat in the Hat Knows a Lot About That! is a hit among young children and their lucky parents and teachers.

Kate also writes the occasional Step into Reading Book as Bonnie Worth. Under her own name, Kate wrote The Dragon Keepers and the Dog Diaries for middle-grade readers and The Centauriad for young adults. Her newest book The Enchanted Dress Shop has been optioned for the screen. She lives in New Paltz, New York, with her husband and two horses.

Born in Springfield, VT, Joe Mathieu is the illustrator of over 150 popular picture books, including Sesame Street books, "We're Going on a Lion Hunt", "Mrs. Millie Goes to Philly!", and "Pick a Pumpkin, Mrs. Millie!". He has a BFA from the Rhode Island School of Design and has been a freelance illustrator since 1971. Joe lives in Hudson, Massachusetts and enjoys cycling and ragtime piano.