Bach's vocal oeuvre contains a significant number of movements (about thirty-five), including but not limited to those in modified da capo form, with a concluding reprise of opening thematic material in the subdominant key. Some of these ‘subdominant returns’ involve strict parallelism, whereby the entire A section returns at the new pitch, thus transforming the original ‘departing’ modulation from I to V into a ‘returning’ modulation from IV to I. Many subdominant returns, however, occur in a range of contexts, which resist straightforward formal categorization. One example is the opening chorus from the St Matthew Passion. While the unusual da capo in this movement has elicited provocative commentary by Karol Berger and others in recent years, the significance of the subdominant return (here and elsewhere) has not been examined in depth. This study begins with a comprehensive survey of subdominant returns in Bach's vocal oeuvre, and then examines cyclic and linear aspects of form through detailed analysis of six movements that exhibit this procedure.