This book explores the phenomenon of language change, with a particular focus on the social contexts of its occurrence and its possible motivations, including speakers' intentions and attitudes. Using wide-ranging case studies presenting new or little-known data, Jones and Singh draw a distinction between "unconscious" and "deliberate" change. The discussion on "unconscious" change considers phenomena such as the emergence and obsolescence of individual languages, while the book also includes detailed discussion on "deliberate" change, traditionally marginalised in favour of explorations of the "unconscious" variety. The sections on "deliberate" change focus on issues of language planning, including the strategies of language revival and revitalisation movements, and also include a detailed exploration of what is arguably the most extreme instance of "deliberate" change, language invention for real-world use. As a student-friendly text which covers a wide variety of language situations, it also makes a clear, but often ignored, distinction between concepts such as language policy and planning, and language revival and revitalisation, and the innovative case studies which permeate the text demonstrate that real-life language use is often much more complex than theoretical abstractions might suggest. This book will be extremely useful to students on a variety of courses including sociolinguistics, historical linguistics and language policy and planning.