The bookstore where I work part time categorises books by 9-12 and then goes straight to young adult, which holds books like the vampire diaries and the pretty little liars series which i would estimate are aimed at 16-21 year olds roughly alongside much younger titles like the faerie rebels series by R. J. Anderson which i would say is aimed at around the 12 mark. I think it'd be great to have a separate section called tweenage fiction which holds books for 12-16 year olds. What do you think? Does your local bookstore have a section for this age range? What do they call it?