In recent years, interest has grown among legislators and educators regarding the use of teacher evaluation as a leverage point for increasing the effectiveness of instruction in schools. Though there is an existing body of knowledge around the attitudes and beliefs held by teachers about their own evaluation experiences, very little information exists about teacher evaluation from the perspective of the site administrator. The purpose of this qualitative study was to examine the mental models (beliefs, attitudes, assumptions, and knowledge) held by school principals regarding a new teacher evaluation system. The questions guiding the study were 1) What mental models (beliefs, assumptions, attitudes, and knowledge) do principals hold about the role of teacher evaluation as a vehicle for change in schools; and, 2) Do different school contexts (elementary, middle, and high school) influence the mental models that site administrators hold relative to teacher evaluation? Sixteen principals were interviewed during the fall of 2016 regarding their perceptions of a new teacher evaluation system. The interviews were examined using a constructivist grounded theory methodology. Results of the analysis revealed three major themes with subthemes: 1) Tension: The Importance of Doing Teacher Evaluation and Feeling Overloaded and Overwhelmed, 2) Desperately Trying to Figure It Out: It's a Catch-22 System and Getting a Handle on Time Management, and 3) Glimpses of Resolution. Findings in this study indicated that principals' mental models play a significant role in the change process as related to school initiatives. [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.]