I thought I was around 10 when I read this, and I just recently handed it off to my 12 and 13 year old daughters because I didn't think they were ready to read it earlier. Go figure. 

Margaret is a great character because she says what we were all thinking about - growing up, periods, how icky they were, how exciting and strange it all seemed. Being in that middle place between being a little girl and becoming a woman and not really knowing where you fit in. At the time it must have been revolutionary to talk about personal things like this, and I can easily see why this book was banned over and over. But to me, this book is a classic, and reading about how Margaret navigates these waters is a helpful reminder that every kid has to grow up and nobody is alone.