PreS-Gr 3 McDonnell's expressive characters, Earl the pooch and Mooch the cat, move from the award-winning "Mutts" comic strip to this slim picture book to answer the question, "What makes Earl's tail wag?" On page after page, readers see a stimulus that creates the response: belly rubs, sitting in a field of flowers, or playing ball. But McDonnell's question is deeper than thatwhat is it about these things that makes Earl so happy? After many humorous false starts (cats are famous for an absence of short-term memory), Mooch provides the answerit's love. McDonnell knows how to use space on a page, create character and affect with a few strokes of his pen, and tell a story using a minimum of words. Children will recognize themselves and their pets in this charming story. Lisa Egly Lehmuller, St. Patrick's Catholic School, Charlotte, NC