Assessments are one of the most important--and often misunderstood--elements of education. In most cases, tests are administered by the state as well as by districts and schools. Assessments at each of these levels have distinct purposes, yield different information, and are part of a powerful, coordinated approach to improving student outcomes. Each year, states are required by federal law to administer an annual summative assessment to all public-school students. These results give policymakers meaningful information to use in targeting resources to the campuses and students with the greatest need, determining when to intervene in underperforming schools and monitoring campus and district improvement efforts. This paper gives policy recommendations to Congress and State policymakers to ensure that valid, comparable, and reliable assessments are available and used in the public education system.