This book has been the most helpful book of all! I have told everyone parent I know about it. I used the methods on my then 4 week old son right after I read the book. He became calm in couple of minutes and then asleep within ten minutes. Before using Dr. Karp's techniques my son was having daily crying sessions that lasted five plus hours and nothing worked to calm him. I am just thrilled that there is something so simple to comfort my baby. I am also pleased that he supports breastfeeding and writes about co-sleeping in a positive way.This book is a wonderful tool for any parent. You will not regret this purchase!