An investigation into the declining supply of principals in two states in Australia revealed that a mosaic of issues surrounds the overall trend towards fewer applications for vacant positions. Looking beyond systemic factors influencing this trend--factors such as the increasing workload of principals--this study discovered why some schools are more affected by a shortage of applicants than others. We found that one of four categories of deterrents was generally involved with declining numbers of applications: location, the size of school, the presence of an incumbent, or difficulties arising from local educational politics. We found, furthermore, that smaller numbers of applicants for vacant positions do not necessarily indicate a decline in interest in school leadership: interest in the principalship remains relatively high but principal aspirants have become increasingly strategic in their applications. Whilst drawing attention, in this paper, to the research finding that numerical interpretations of principal supply have serious limitations, we are keen to acknowledge, briefly, the research data that refers to (a) social and generational changes (b) demographic information, (c) teacher resistance to the modern principalship and how these data explain declining numbers. We also include information about recent changes that go counter to the trend.