The role of the school principal continues to increase in its responsibility and complexity. This narrative study centered around two research questions: 1. What stories do principals tell about their memorable professional development and 2. In what ways do the stories align with Knowles' principles of adult learning theory? Eight principals from the CESA 1 Region of Wisconsin with between three and fifteen years of experience participated in this study. Three of the participants were female and five were male. These principals shared stories of their professional development experiences since becoming a school principal and what impact those experiences made on their work. Additional questions were asked to help the participants reflection the structure and context of those experiences and whether or not those components supported their learning. Transcripts of those interviews were reviewed and analyzed, with the analysis leading to four main themes in the data: Collaboration, Trusted Sources, Individualization, and Relevance. All eight participants included references to collaboration and trusted sources in their recounting of their professional development experiences. The themes of individualization and relevance, though not present in all of the stories, are tightly aligned to Knowles' principles of adult learning theory. Recommendations include ensuring that principals are involved in ongoing, collaborative professional development that will support specifically their instructional leadership, and additional research to help develop practical systems of both content and process that would effectively meet the professional development needs of school principals. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]