The primary concern of this interdisciplinary and empirical study is to explain language switching and language preservation in terms of linguistic behaviours. With reference to the language behaviour of the German-speaking community in Hungary in the last third of the 19th century, the attempt is made to establish whether and to what extent the theory of planned behaviour - one of the most influential attitude and behaviour models in modern social psychology - is in a position to resolve this central and much-discussed problem of sociolinguistics. In so doing, the book sets out to indicate the sociolinguistic benefits of socio-psychological ideas that in the relevant research have hitherto only been drawn upon in the form of isolated concepts regarded in isolation.