Starting in 2011, Boston Public Schools (BPS) implemented major reforms to its teacher evaluation system with a focus on promoting teacher development. We administered independent district-wide surveys in 2014 and 2015 to capture BPS teachers’ perceptions of the evaluation feedback they receive. Teachers generally reported that evaluators were fair and accurate, but that they struggled to provide high-quality feedback. We conduct a randomized controlled trial to evaluate the district’s efforts to improve this feedback through an intensive training program for evaluators. We find little evidence the program affected evaluators’ feedback, teacher retention, or student achievement. Our results suggest that improving the quality of evaluation feedback may require more fundamental changes to the design and implementation of teacher evaluation systems.