Oklahoma is one of 16 states electing to use an A-F letter grade as an indicator of school quality. On the surface, letter grades are an attractive policy instrument for school improvement; they are seemingly clear, simple, and easy to interpret. Evidence, however, on the use of letter grades as an instrument to rank and improve schools is scant…

Background/Context: Despite problems with accountability systems under No Child Left Behind, the policy has been widely commended for exposing the depth and breadth of educational inequality in the United States. As states implement new accountability systems, there is growing concern that attention to achievement gaps and the performance of…