Mary Pope Osborne is the author of the New York Times number one bestselling Magic Tree House series as well as co-author of the Magic Tree House Fact Tracker series, along with her husband, Will, and her sister, Natalie Pope Boyce. For more information, visit the Magic Tree House(R) website at MagicTreeHouse.com! Natalie Pope Boyce and Mary Pope Osborne are sisters who grew up on army posts all over the world. They work together on Magic Tree House(R) Fact Tracker books to give readers information about the places, time periods, and animals that Jack and Annie discover in their Magic Tree House adventures. Natalie makes her home in the Berkshire Hills of Massachusetts. Mary is the author of all the Magic Tree House(R) fiction titles, as well as many more books for kids. For more information, visit the Magic Tree House(R) website at MagicTreeHouse.com! Isidre Mon s is a Spanish artist best known for his comic-book work. He has also illustrated numerous children's books, such as Cloudy with a Chance of Meatballs 3: Planet of the Pies by Judy Barrett, as well as several of Cynthia Rylant's Henry and Mudge stories. Mon s lives in Barcelona, Spain.