This brief presents the case for the reform of assessment systems as an essential component of systemic reform. The scope includes ways to share conceptual understanding among all stakeholders in the educational system, ways to evaluate the impact of systemic reforms in terms of student attainment of relevant goals, and ideas on how assessment can play a major role in guiding systemic reform. The formidable body of work done to develop new assessment systems is described. The ideas contained in this brief are generic and equally applicable to science education. (Author/DDR)