This qualitative study investigated the teacher evaluation systems currently in place in diocesan high schools in California and the ways in which those systems could be improved. Diocesan schools are private, Catholic institutions that do not subscribe to federal regulations when creating their evaluation instruments. Measuring effective teaching in a way that is feasible, meaningful, and fosters professional growth is important because effective teachers directly correlate to student success. However, the only comprehensive study ever conducted on teacher evaluations focused on public schools and their tenured faculty. In the private sector, teachers are at-will employees; yet, no research has been done on teacher retention and its relationship with teacher evaluations. This study addressed gaps in the literature by delving into the current teacher evaluation policies and procedures in place at three diocesan high schools in California. Through a case study of relevant evaluation documents, individual administrative interviews, and faculty focus groups, this study produced findings that indicated the current evaluation procedures lack consistency, foster negative perceptions of administration by faculty, are performative, and require too much time to complete. Additionally, this study found teachers and administrators believe evaluations should be tied to professional growth, the culture surrounding evaluations needs to change, and peer feedback is invaluable. Therefore, these positive changes should be implemented in diocesan high schools to provide teachers and administrators with meaningful teacher evaluations. [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.]