This specially commissioned volume considers the processes involved in language change and the issues of how they can be modelled and studied. Theway languages change offers an insight into the nature of language itself, its internal organisation, and how it is acquired and used. Accordingly, the phenomenon of language change has been approached from a variety of perspectives by linguists of many different orientations. This book brings together an international team of leading figures from different areas of linguistics to re-examine some of the central issues in this field and also to discuss new proposals. The volume is arranged in six parts, focusing on the phenomenon of language change, linguistic models, grammaticalisation, the social context, contact-based explanations and the typological perspective.