Linguists believe that there are between 6,000 and 7,000 living languages in the world today (Grenoble and Whaley 2006). At least half of these are endangered and are not predicted to survive the twenty-first century (Crystal 2000). When a language ceases to be spoken, it is referred to as a dead (or extinct) language.1 A living language is a dynamic system of communication, which is transmitted from generation to generation, changing over time as it adapts to meet new communicative needs. Generally speaking, a language is considered endangered when the likelihood arises of it ceasing to be used in this manner. The downward slide from full vitality toward death is referred to as language decline. Death is not the inevitable end point of decline, but it is a possibility if the process is not arrested. In this chapter we present an overview of the causes of, and responses to, language decline. We focus on the issues we feel best able to address given our experience and training, referring the reader onward to the relevant literature for those issues that have been dealt with comprehensively by other authors.2 We begin with a word about what we mean when we use the term “endangered” with reference to languages.