One of the failings of teacher evaluation systems in the United States has been their reliance on the school principal alone as the person expected to observe teachers, mentor those who struggle, document concerns and processes, and make the final call on whether to recommend dismissal. Given the enormous scope of their duties, it's simply unfeasible for principals to give the level of attention needed to supporting and evaluating teachers. One solution to this problem is peer assistance and review (PAR) programs, which rely on highly expert mentor teachers to conduct some aspects of the evaluation and provide assistance to teachers who need it. The PAR system includes two key features: (1) the expertise of consulting teachers, skilled teachers who have released time to serve as mentors to support fellow teachers in the same subject areas and grade levels, and (2) a system of due process and review that involves a panel of both teachers and administrators who recommend personnel decisions based on evidence from the evaluations. The majority of intervention candidates improve. Those who don't improve leave teaching without extended legal proceedings because due process is built into the design of the model. Engaging expert teachers through programs like PAR can help districts build systems that link evaluation, professional development, and collegial learning.