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-illustrator.
Gerald 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 I am Invited to a Party!, Piggie is invited to her first party. But what will she wear? Gerald, the party expert, knows just how to help … or does he? Told entirely in speech bubbles with a repetitive use of familiar phrases, this highly original book is perfect for children just learning to read.