This chapter identifies the difficulties and explains how these are dealt with and how language names are handled in the Catalogue. A guiding principle with important consequences for naming languages is to make the Catalogue of Endangered Languages maximally useful and maximally accessible to the widest possible range of users and audiences, recognizing their different needs and respecting their preferences. The chapter addresses several major challenges for the naming conventions used in the Catalogue of Endangered Languages. The first challenge is that of multiple names associated with a single language, and how these are to be represented in the Catalogue of Endangered Languages. The second challenge is that the names for languages in the academic or popular literature and the names preferred by speakers of the languages often do not match. The third challenge is that there can be more than one preferred name for a language among its speakers, even though linguistically it is the same language.