The Lexile system by Metametrics is a popular rating system used widely in the United States and elsewhere which purports to rate both the reading level of books and the ability level of students on the same scale. Unfortunately, the reading level algorithm does not take into account the vocabulary or syntactic patterns used in the texts, but only mechanically measurable qualities of the text such as average sentence and word length. Parents, teachers and librarians use the system to classify books and determine which ones might be suitable for students. It simply does not work for L2 students. This paper will attempt to explain why the system does not work and the potential dangers of employing it for students for which it was not designed.