How does a language community sustain their language in the face of ever-increasing forces of language shift? This volume, both a textbook and a handbook, is the result of ten years of reflection by the authors in light of SIL International's 80 years of fieldwork in local language communities. Using the Sustainable Use Model detailed here, readers learn how to advise maintaining use of their language at a sustainable level. This could include, not only the level of active literacy, but also levels of orality and identity. The book is aimed at "on the ground" workers involved with a community, to address issues arising from language and culture contact. M. Paul Lewis (Ph.D., sociolinguistics, Georgetown University) did fieldwork in Guatemala, was general editor of the Ethnologue(R), and is a Sociolinguistics Consultant with SIL. His research interests are language endangerment, language policy and planning, and language documentation. He has consulted and trained on six continents. Gary F. Simons (Ph.D., linguistics, Cornell University) is Chief Research Officer for SIL and Executive Editor of the Ethnologue(R). He was involved in language development in Papua New Guinea and the Solomon Islands, co-founder of the Open Language Archives Community (OLAC), and co-developer of the ISO 639-3 identifiers for the world's languages. "In this clearly written monograph, Lewis and Simons lay the groundwork for those who [work] with members of local language communities, to help them implement diverse activities that most effectively lead to a sustainable level of language use. They build appropriately upon the groundbreaking work that was carried out several decades ago by sociolinguists such as Charles Ferguson, Robert Cooper, and Joshua Fishman." - Adapted from the Foreword by G. Richard Tucker