This poster describes Minneapolis Public Schools' teacher evaluation system and details findings from a psychometric analysis of the Standards of Effective Instruction rating instrument. The poster will be highly relevant to educational evaluators contending with teacher evaluation reform. In Minnesota and nationally, policymakers and educational leaders are devoting more attention and resources to data-driven teacher evaluations. Ratings by trained observers and value-added scores are common features of the new systems. To what degree are the ratings valid measures of teacher effectiveness? The poster will share lessons learned and final results of the psychometric analysis.