This paper is intended to support school authorities by summarizing research on professional development. The term professional development is used in a context that encompasses related terms such as staff development, training and in-service. The paper covers conceptions and understandings of professional development, processes and approaches related to professional development, effective environments for professional development, evaluation of professional development, and indicators of effectiveness. An extensive annotated bibliography is provided. [InPraxis developed this report for the School Improvement Branch, Basic Learning, Alberta Education.] (Contains 4 tables.)