The successful school district approach is one of several methodologies—such as the professional judgment approach, the evidence-based approach, or the cost function approach—that states have used to estimate the total amount individual school districts would need to spend so students have a reasonable chance of meeting a state’s student performance expectations. All of these approaches are rational ways to estimate district costs: The successful school district approach examines the spending of districts identified as meeting state education standards; the professional judgment approach relies on calculating the costs of resources deemed necessary by a panel of educators; the evidence-based approach focuses on research that estimates the value of specific resources in improving student performance; and the cost function approach examines the statistical relationships between resources and ...