I never leave reviews, but I'll make an exception for this one!
My daughter is just 9, and the first signs of puberty are appearing, so I needed to explain what was happening. She has no previous knowledge of puberty, sex or any related subject.
This book is written in concise and informative sections covering everything you need it to; periods, boobs and bras, hair in new places, sex, emotions, spots, exercise, eating well, keeping clean, and everything else you can think of! I can honestly say that at no point have I felt that anything relevant was overlooked. It also has a section about changes in boys (I think there is a 'boy' version of this book available too).
It's beautifully illustrated in colour throughout, and has easy to understand diagrams where appropriate.
It's taken much of the mystery and fear out of what could have been a scary time for her, and has opened the way for us to have sensible but lighthearted chats about how she will change in the coming years. I must admit that broaching the subject with her was a terrifying thought, but this book has got the ball rolling.
It's appropriate for approximately age 9 - 12 (although would probably be OK for slightly younger/older girls too), and is written in a way that is easy to read and in language she understands - proper names and scientific terms are all explained too.
I cannot recommend this book highly enough, and as my daughter has read it 3 times in the few days since she received it, I guess she'd recommend it highly too!