Making Friends for Your Child is a parenting book where it is hidden in the shelf in Susan Heffley's closet.
During the events of Hard Luck, Susan told Greg that he needs to go outside. Asking his Magic 8 Ball, Greg declines her request and instead secretly hides in her closet, where he discovers this book along with a bunch of stuff that his mom uses in certain situations.
Seeing the book, Greg determines that this is the book that she uses to try and help him find new friends after his best friend, Rowley Jefferson ditches him in favor of his girlfriend, Abigail Brown.[1]