This paper reports on research into the professional development practice of principals in the Diocese of Parramatta, which administers a system of approximately 75 schools in the west of Sydney, Australia. A survey of 46 principals gathered data on respondents' qualifications, association membership, participation in Catholic Education Office professional development activities and in inservices provided by other agencies, conferences attended, other activities contributing to professional development, valued forms of professional development, perceived professional development needs, preferred methods of delivery, and tertiary credit. The data indicated that the principals in the Parramatta diocese are, by and large, an experienced and highly qualified group and in general they participate regularly in professional development activities. The most commonly attended forms of professional development are conferences organized by the principals' associations. The most valued professional development activities are those classified as "learning on the job" or involving interpersonal skill development. Female principals, lay principals, and primary principals attended more professional development activities than their male, religious, and secondary counterparts respectively. In light of these results, three major initiatives were developed to address the professional development of principals at three stages: pre-appointment, induction, and ongoing development. (JDD)