Multilingualism, including bilingualism, has become internationally important today because of the increasing interdependence between countries, regions and continents, and because of increasing concern with preserving linguistic and cultural diversity. This book is a comprehensive introduction to research on multilingualism. Although psychological aspects predominate, it provides a multidisciplinary perspective on the individual and societal consequences of multilingualism, bringing together insights from linguistics, pedagogy, cognitive neuroscience, sociolinguistics and psycholinguistics. The book underlines the normality of speaking and using more than one language, and serves to dispel many myths and fears in this regard. Besides theoretical issues, it also provides recommendations on how to promote multilingualism in children from a dominant language group, and how to maintain all languages of students from ethnic communities by means of education.