Used throughout the world since earliest times as a common means of communication, sign language was particularly well developed among the Plains Indians of North America. The present study, a significant document in the history of American anthropology, was originally published in 1881 as part of the first annual report of the Bureau of American Ethnology. The author was a retired U.S. Army officer and bureau employee who was perhaps the foremost expert at that time on American Indian sign language. His exceptional knowledge of the subject produced a classic body of research data, still cited by anthropologists. The book begins with theories and observations about the genesis and universality of sign language, as well as its use by animals, children, and uninstructed deaf-mutes. Following an account of his research and methodology and suggestion for further research, the author devotes several pages to describing and illustrating signs used for specific words — from "antelope," "trade," and "yes" to such sentences as "Who are you?" "What is your name?" and "How old are you?" Especially interesting are 40 pages or so of narratives or dialogues, most given both in sign language and in oral paraphrase. Throughout the book, clearly diagrammed illustrations indicate proper movements of body and hands for signing. Students of linguistics and anthropology — anyone fascinated by this age-old method of communication — will welcome this inexpensive reprint of a long-unavailable treasure.