This qualitative study explored the degree to which knowledge management strategies addressed teacher professional learning at the high school level. In the setting of a Connecticut public high school, interviews were conducted which explored teacher perceptions of knowledge sharing practices in the school and how those practices influenced their professional learning. The research literature on Knowledge Management was used to develop the proposition that guided this study: knowledge management practices enhance the sharing of professional knowledge among teachers and, in turn, enhance teacher professional learning. The results were analyzed using a constant comparative method. The results indicated that informal knowledge management practices were more influential than formal practices on teacher professional learning. The results also indicated that the school environment was a critical factor in teachers' professional learning. The limitations to this study included: credibility and transferability of the data, biases of the researcher, and the dependability and verification of the finding. The results may be used to inform school leaders about effective knowledge management practices for schools which can enhance knowledge sharing, increase teacher professional learning and ultimately improve educational practice in the classroom. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]