Research shows that traditional, principal-led teacher evaluation in the United States is desperately in need of reform. While principals aspire to be instructional leaders, their attention is spread thin across their vast managerial and instructional leadership responsibilities. For many principals, teacher evaluation falls by the wayside. Peer Assistance and Review (PAR) programs offer an alternative to the traditional system of teacher evaluation and supervision. Principals in these programs share responsibility for the evaluation and support of novices and struggling veterans with expert Consulting Teachers (CTs). This paper investigates the principal's role in PAR programs in seven districts, as well as the strengths and weaknesses of how supervision and evaluation are accomplished under PAR, according to the principals in this study. The majority of principals in this study said that PAR provided a superior system of mentoring and evaluation for novice teachers than what principals alone could offer under a traditional system. Stakeholders reported that the Novice PAR program alleviated the typical challenges that principals face in teacher evaluation--a lack of time and expertise, and political and cultural roadblocks. Under PAR, principals collaborated with CTs who carried out the majority of the mentoring and evaluation of teachers. Principals and CTs demonstrated that authority for evaluation could be effectively shared. Several different models for sharing these responsibilities were evident in this study. Many principals were reluctant to use the Intervention component of PAR, designed to assist struggling veteran teachers. Principals found the referral process to place a teacher on Intervention to be too cumbersome and politically and culturally difficult. Those principals who did utilize Intervention reported it to be useful and preferable to a traditional process. Nonetheless, most principals said that Intervention did not adequately resolve many of the problems of the traditional evaluation system for veteran teachers. Despite these challenges with Intervention, the majority of principals in this study reported that PAR increased the instructional capacity of their schools by providing more effective supervision and evaluation than a traditional system could offer. Furthermore, principals and other stakeholders credited PAR with fostering a collaborative culture focused on instructional improvement. [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.]