Eyak (dAXunhyuuga’) is the traditional language of the Copper River Delta region of the Gulf of Alaska. This posthumous publication reflects Michael Krauss’s systematic effort to document every aspect of the language, working closely with the last remaining fluent speakers. Adopting a theory-neutral approach, Krauss focuses on detailed description, providing exhaustive exemplification, as well as ample discussion of comparative and conflicting data from the related Tlingit and Dene (Athabaskan) languages, making the work particularly useful for Dene scholars. Non-specialists will find a window into the structure of a highly synthetic and typologically unusual language. This comprehensive work will also serve as a useful reference for the growing dAXunhyuuga’ reclamation effort.