A comprehensive account of an endangered Scandinavian language, with an introduction to its history, sociolinguistics, and status. Elfdalian is the language traditionally spoken in Älvdalen, central Sweden. Due to its linguistic difference from Swedish, several attempts have been made in Sweden to acquire official recognition of it as a minority language. However, despite the growing interest in documenting and revitalizing Elfdalian, it is still regarded as a dialect. As one of the best-preserved members of a larger but lesser-known sub-branch of the Scandinavian languages called Dalecarlian (or Dalmål), Elfdalian is a unique language to study. The purpose of this grammar is to account for Late Classical, or Preserved Elfdalian from linguistic, historical, and sociolinguistic angles, and to make the language, including both its archaic and innovative features, accessible to a wider audience. Grammar of Elfdalian serves as a valuable resource for Ölvdan locals who wish to revitalize or retake their language, for those who wish to transmit the language to others through preschool, school, or adult instruction, and for people who wish to study a North Germanic language for the first time. Linguists may find Elfdalian interesting from the angle of its language structure, as well as from the perspectives of sociolinguistics and language policy.