The rise of the accountability movement in education has resulted in the proliferation of school report cards, school ratings and rankings, and other kinds of performance reporting for public consumption and policy use. To understand the strengths and limitations of school rating systems and the role they play in shaping public perceptions and school improvement practices, this paper situates rating systems within the broader field of comparative organizational assessments and neo-institutional theory; describes school rankings and rating systems in use by states and consumer-oriented enterprises; and details four aspects of school ratings (measurement, transformation, integration, and presentation) that affect their use and interpretation.