Author: Willems, Mo
Interest age: from c 5 years 
Published 01/05/2012 by Walker Books Ltd in the United Kingdom as part of the Elephant and Piggie series 
Paperback | 64 pages
One of a series of delightfully humorous award-winning tales for beginner readers from an internationally acclaimed author-illustratorGerald is careful. Piggie is not. Piggie cannot help smiling. Gerald can. Gerald worries so that Piggie does not have to. Gerald and Piggie are best friends. In My Friend is Sad, Gerald is sad. How can Piggie be happy if Gerald is sad? Told entirely in speech bubbles with a repetitive use of familiar phrases, this highly original book is perfect for children just learning to read.