School grades were introduced in Florida in 1999, the first such A-F model for reporting on school accountability in the nation. The purpose of school grades was to make it easy for parents and citizens to understand and compare how schools were performing academically, and to compel low-performing schools to improve. Since then, the A-F grades have been the consistent standard system for measuring school performance results in Florida. However numerous changes in the standards, tests, and even the formula used to calculate school grades over this time has caused much confusion -- and occasionally mistrust -- over what these grades actually mean. In the coming year, Florida will be implementing new standards and adopting new assessments that will require elements of the school grades formula to be changed once again. Rather than continuing to make piecemeal, disconnected adjustments whenever circumstances like this arise, Florida should take this opportunity to conduct a top-to-bottom review of the school grading system. By identifying what has worked well in the past, how students' needs may change in the future, and what else should be updated, state decision-makers can make sure that the system is more stable, consistent and meaningful moving forward. This brief takes a closer look at how the school grades calculation formula works, identifies the sources of some of the most prominent issues of confusion in recent years and offers suggestions for how to address these issues now to avoid further problems down the road.