This thesis deals with the tone accent opposition in the so-called “Rule B area” in Franconian. Rule B is known for its reversal of tonal melodies: in 1921, Adolf Bach published a description of the Arzbach accents, stating that the tonal melodies in Arzbach display a reversal of those in the rest of the area (Rule A). The study at hand not only provides crucial but as yet missing empirical data on Rule B but also suggests synchronic and diachronic typological analyses of the phenomenon. Newly gathered phonetic data from the Arzbach dialect show that the tone accents in Arzbach are reversed in declaration but not in interrogation, where they strongly resemble the Rule A contours. This important observation was unreported so far. On the basis of these findings, detailed synchronic autosegmental analyses for Arzbach and three other Franconian dialects show that we can understand the tone accent opposition as one of different foot structures for the two accents (resulting in head domains of different size). All analyses are formalized in Optimality Theory. The diachronic section of the thesis explores the origin of the semi- reversed tonal contours in Rule B. It argues that Rule B and Rule A developed out of a common predecessor but adapted in different ways to declaration melodies from non-accent dialects, which lead to opposite declarative contours. This study is of interest to phonologists concerned with tone, prosodic structure, and their interaction. Furthermore, it addresses (acoustic) phoneticians as well as dialectologists, especially those interested in Germanic prosody.