Evidence from the field indicates that many good candidates are not applying for principalships in Australian Catholic schools. Research aimed at developing an instrument to assess their reasons for not applying was conducted in New South Wales, Australia. A sample of 977 assistant principals, religious education coordinators and other coordinators were used in the evolution of a survey instrument. Scale development procedures resulted in a 32-item questionnaire with 8 underlying scales (namely, Unsupportive External Environment, Systemic Accountability, Lack of Expertise, Personal and Family Impact, Explicit Religious Identity, Gender Bias, Interview Problems, Loss of Close Relationships). Validation data indicated that this instrument-the Impediments to Leadership Succession Inventory-has sound structural characteristics. Use of this instrument revealed that respondents who perceived clear disincentives and systemic and societal devaluing of the work of principals were less inclined to apply for a principalship.