Differentiating state services to support district and school improvement makes sense for two reasons: (1) support is most effective when targeted to the specific needs of the district or school, based on both performance data and diagnostic data about prevailing operational and professional practice; and (2) state resources of time and money are more efficiently allocated when targeted to the specific needs of the district or school rather than applied in a blanket manner to all districts or schools in a common strata of improvement status. In more recent years, many states have established means for differentiating districts and schools based on finer-grained analysis of student performance and diagnostically determining gaps in operational and professional practice that contribute to student outcomes. Likewise, the protocol for diagnosis has become more sophisticated: higher functioning districts and schools are provided instruments, tools, and procedures for self-diagnosis.