Increasing public criticism of traditional teacher evaluation systems based largely on classroom observations has spurred an unprecedented shift in the debate surrounding educational accountability policies, specifically about the purposes for and measures used to evaluate teachers. In response to growing public demand and associated federal mandates, states have been prompted to design and implement teacher evaluation systems that use increasingly available, statistically complex models (i.e., value-added) intended to isolate and measure the effects of individual teachers on student academic growth over time. The purpose of this study was to examine the perceptions of school administrators and teachers within one of the largest school districts in the state of Arizona with regards to the design and implementation of a federally-supported, state policy-directed teacher evaluation system based on professional practice and value-added measures. While much research has been conducted on teacher evaluation, few studies have examined teacher evaluation systems in context to better understand the standards of effectiveness used by school administrators and teachers to measure system effectiveness. The perceptions of school administrators and teachers, considering their lived experiences as the subjects of the nation's new and improved teacher evaluation systems in context, must be better understood if state and federal policymakers are to also better recognize and understand the consequences (intended and unintended) associated with the design and implementation of these systems in practice.