We started out with the Baby Wise book recommended by our pediatrician because our 8 month old was not sleeping through the night. We had great success using the information from the book and our daughter is now sleeping 10-12 hours without nursing or waking us up. So, I decided to buy the other books by this author. Potty Wise is helping me potty train my 3 year old that regressed when we brought our baby home from the hospital and Baby Wise II and PreToddler Wise are helping me not only with my growing baby but also with some things I missed along the journey with my 3 year old. These are great books for basic guidelines and applicable principals.