UNESCO Atlas of the World's Languages in Danger

The reference work UNESCO commissioned to record which of the world's languages are losing intergenerational transmission and how severely, edited by linguist Christopher Moseley with contributions from a worldwide network of regional language specialists, published in successive print and interactive editions since 2001 (third print edition 2010). Each entry is assigned one of five degrees of endangerment: vulnerable, definitely endangered, severely endangered, critically endangered, or extinct, based on the specialists' own field assessment of whether a language is still being passed to children. As a compiled scholarly assessment drawing on a global network of named linguists rather than a single institution's own administrative record, it sits at this atlas's top tier alongside Ethnologue. It is the right source for a living language's degree of endangerment. It says nothing about a language's classification, speaker count or geographic distribution beyond what bears on vitality, and it does not classify dead or purely liturgical languages at all, since a language with no remaining speakers to lose is outside its scope by design.