The concept of bilingualism has been analyzed for a very long time. Its definitions range from native-like competence in two languages to a minimal proficiency in a second language. Hence one might question why no consensus has been reached in this matter. The authors of this volume imply that there exists a number of theoretical and methodological difficulties raised by older definitions. The notion of bilingualism has to be investigated from different perspectives reflected by the dimensions each individual intends to diagnose. The aim of the book is to review critically the state of the...