Purpose: The purpose of this qualitative case study was to identify and describe the strategies that California public high school principals utilized to develop a growth mindset in classroom teachers. Methodology: This qualitative case study used interviews from 12 high school principals to gain an understanding for how they supported a growth mindset in their classroom teachers. The population for the case study was northern California high school principals, and the sample included high school principals from Napa, Sonoma, Solano, Marin, Alameda, and Contra Costa counties. To participate in the study, principals needed to be serving in at least their third year as principal at their school site, were principal at the time their school earned its most recent WASC accreditation, and received a WASC accreditation term of six years with a two day visit or better. Findings: A total of 15 common themes emerged among the 3 research sub-questions of the study. These findings touched on the importance of school culture, providing feedback to teachers, and celebrating successes. Additionally, themes emerged about the characteristics of teachers with a growth mindset, including their desire to try new things and learn from feedback. Conclusions: Four main conclusions were drawn based on the findings of this study. First, principals should intentionally address the culture at their school. Second, principals should determine and communicate a clear school-wide focus. Third, principals should find creative ways to celebrate teachers' successes. Lastly, principals should invest in the professional learning community (PLC) structure at their schools. Recommendations: Recommended action items based on the research included districts providing ongoing instructional coaching training to principals so that they can better guide teachers in reflection and learning. School districts need to also explicitly train principals in the concept of growth mindset. Furthermore, school districts need to reflect on and evaluate the effectiveness of their teacher evaluation process. Principals should explore creative and innovative ways to recognize teachers for their successes and implement professional learning communities at their school sites. Additionally, principals need to find ways to include the student point of view in the teacher learning process. [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.]