In the last 30 years, a universal recognition that almost 40% of the world's 7000 languages are in danger of extinction has spurned a new field of interdisciplinary study of under-resourced and under-privileged languages. This textbook speaks to the inceasing interest in endangered languages as an important sub-field of linguistics, and provides an overview of the historical, geographical, and social factors which have led to language endangerment. As the only book available on the topic designed for course use, this text offers comprehensive coverage of both language endangerement and language revitalization, and sets the foundation for further study, discussion, and reading. Additional features of this text include: * Case studies of language documentation, preservation, and revitalization efforts * Suggested further reading at the end of each chapter * Activities that illustrate changes to linguistic structure at different stages of linguistic erosion and language change due to contact * A companion website which includes videos, links to websites relevant to endangered languages, and additional readings