Ever since the origins of both linguistics and evolutionary biology in the 19th century, scholars have noted the similarity between biological evolution and language change. Yet until recently neither linguists nor biologists have developed a model of evolution to apply across the two fields. Explaining Language Change presents the first integrated theory of all aspects of language change which builds on the pioneering ideas of Richard Dawkins and David Hull in biology and philosophy of science. It provides a framework for assessing current theories and advances new ideas about grammatical reanalysis, conventional and non-conventional use of language, the structure of speech communities, language mixing, and the notion of 'progress' in language change. This is an important new study which reintegrates sociolinguistics and historical linguistics and weaves together research on grammatical change, pragmatics, social variation, language contact and genetic linguistics.