In the first part of the study, an overview over Upper Silesia and the numerous historical language shifts in this area is given. With at least five language shifts and three phases of complete language loss, Upper Silesia constitutes quite an illustrative case for loss and maintenance in a region. In part two, a conceptualisation of language shift is presented. Two approaches to language shift are then developed, the processual and the correlative. The latter emphasises the competence dimension, divided into an analysis of one language only, German, and an analysis of languages as components of multilingual profiles. Part three presents examples of analyses of isolated German, using the correlative approach. The results in both domains show that German is tied to an urban milieu and has a dominant function as a professional language with high prestige. Part 4 demonstrates the use of multilingual profiles, now from a processual perspective. The analyses show a clear consolidation of Polish with an as yet undecided competition between Upper Silesian and German as second languages. The tendency in the direction of the trilingual profile German/Polish/Upper Silesian seems to have a future if the domains of use stabilise.