I bought this when my son was 9 months old and not sleeping through the night. After an extended trip to visit family (and sleeping with us in the hotel), we couldn't get him to sleep in his own room again. I was a prisoner in his room for sometimes hours at night trying to get him to sleep. I didn't want to make him cry it out, but after months of misery and spending a fortune in books that didn't help, we tried this method. Although he had to cry, I had the freedom to do it as gently as possible. I followed the steps and within a week, he was sleeping through the night!