I bought this book for my (almost 3yr old) son, whom I had been toilet training for over a month. He had no problem with mastering weeing in the potty/toilet very early but I was having real trouble with pooing... I am certain that he knew what was required but just did not want to do it! He absolutely loves books so I ordered this and literally the day afterwards he went in the toilet instead of in his pants and we have not had a single accident since. I have recommended this to friends who are also potty training and I think this book is great for both introducing the concept AND if you find it's not working out. Most toilet training books are only useful at the very beginning and it's hard to find something encouraging and fun if you've started but it's not going well. There are 'flaps' (i.e. nappies) to lift on almost every page and if your child is nosey and inquisitive like mine (and the mouse in the book), they are sure to find this amusing. He still likes to read it now, and I will certainly be using it for my youngest son when I have the joy of training again in a couple of years!