Biographical research on Mozart’s pupils that is based on archival primary sources has been sadly neglected by scholars. Except for a short and highly entertaining article by Gustav Gugitz and two publications in the 1960s, Mozart scholarship still lacks a comprehensive study on a topic that is likely to provide us with a fascinating insight into Mozart’s social background, his pedagogical methods and performance practice in eighteenth-century Vienna. I think there are two reasons for this lacuna: first, the fashionable (and comfortable) assumption that all possible research has already been done, and second, the fact that this kind of archival work is basically restricted to the archives of Vienna. Delving into the lives and careers of Mozart’s pupils Barbara Ployer and Josepha Auernhammer soon leads us to areas that are not commonly associated with musicology: basic genealogy and the identification of private venues and apartments in which Mozart performed his piano concertos. After all, the actual size of these rooms, many of which do not exist any more, has never been the subject of research. Owing to the fragmentary state of the sources and the small number of plans from the eighteenth century that have been preserved, this difficult project is still in its early stages. I will therefore try to point to future directions for documentary research and give an overview of the new biographical data that I have found.