It all depends on reading ability of course, but I bought this book for my 9-year-old and she really likes it. We are reading it together, which I didn't expect, because there are many "challenge" words in it. The main character, a mouse, explains (and eats) words from a dictionary. Many are well beyond the 4th grade level.I like that it is interesting to my daughter yet really challenges her to expand her vocabulary. I doubt many children around her age would read it eagerly if there isn't an adult nearby to help navigate the difficult words.