This text discusses the nature and causes of language change. The authors consider how far changes in morphology cause changes in syntax. They examine such phenomena from the perspective of syntactic and psycholinguistic theory, in particular addressing the issues raised by the hypothesis that grammatical change is driven by how children acquire language. Theoretical questions are discussed in the context of change in a wide variety of languages over a range of periods. The authors are distinguished scholars from the USA, Canada, Japan, Brazil, Australia, Portugal, Italy, Greece, and the UK.