'The claim that language acquisition is responsible for change is often not much more than a theoretical slogan. This book takes this claim seriously and convincingly confronts language change with recent findings from L1 and L2 acquisition, leading to an important reconsideration of the role of both.' Fred Weerman, University of Amsterdam A theory of diachronic change based on studies of language acquisition Under which circumstances does grammatical change come about? Is the child the principle agent of change as suggested by historical linguistics? This book discusses diachronic change of languages in terms of restructuring of speakers' internal grammatical knowledge. Efforts to construct a theory of diachronic change consistent with findings from psycholinguistics are scarce. Here, these questions are addressed against the background of insights from research on monolingual and bilingual acquisition. Given that children are remarkably successful in reconstructing the grammars of their ambient languages, commonly held views need to be reconsidered according to which language change is primarily triggered by structural ambiguity in the input and in settings of language contact. In an innovative take on this matter, the authors argue that morphosyntactic change in core areas of grammar, especially where parameters of Universal Grammar are concerned, typically happens in settings involving second language acquisition. Based on a variety of case studies, this discussion sheds new light on phenomena of change which have occupied historical linguists since the nineteenth century and will be welcomed by advanced undergraduate and graduate students as well as researchers in the fields of historical linguistics and language acquisition. Jürgen M. Meisel is Professor Emeritus at the University of Hamburg and Adjunct Professor at the University of Calgary. Martin Elsig is Research Assistant at Goethe University, Frankfurt/Main. Esther Rinke is Professor of Romance Linguistics at Goethe University, Frankfurt/Main. Cover image: School Scene in the Middle Ages, 1479 (c) akg-images. Cover design: [EUP logo] www.euppublishing.com