The comprehensive analysis of the segmental and metrical system of the Swiss German dialect of Thurgovian provides a significant contribution to both phonetic and phonological theory. Based on the author's original fieldwork and experimental investigations, it is the first in-depth study of this area, tracing it back also to its Old High German roots, particularly that of the dialect of Notker. Quantity alternations - notably word-initial long/short consonantal alternations - asymmetric neutralization of phonetic-phonological contrasts, stress and weight are most prominent among the theoretical issues on which Thurgovian phonology is brought to bear.