Eyak (dAXunhyuuga’) is the traditional language of the Copper River Delta region of the Gulf of Alaska. Smallest of the Alaska Native languages, Eyak had nearly been forgotten by the scientific community by the early twentieth century. In 1963, recognizing both the severely endangered status of the language and its critical importance to the linguistic prehistory of Alaska, Michael Krauss began a systematic effort to document every aspect of the language, working with each of the few remaining speakers. Drawing on more than fifty years of research, this grammar provides the first comprehensive record of Eyak phonology, morphology, and syntax. Adopting a theory-neutral approach, Krauss focuses on detailed description, providing exhaustive exemplification from the now closed corpus. The grammar includes 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 here 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.