High-quality assessments are vital for ensuring a sound and equitable education for all students. Tests are used to measure what students know and can do, and this information is very important for both instructional and accountability purposes. This brief, which should be read as a complement to "High-Quality College and Career Ready Assessments" [ED559395], provides an overview of the main assessment provisions contained within the "Every Student Succeeds Act of 2015" (ESSA). In response to criticisms, ESSA takes steps to reduce the number of unnecessary, duplicative, or burdensome tests being administered in our nation's schools. ESSA also offers a series of new flexibilities to be used for the development of high-quality assessments that better meet the needs of students. These changes to the law present state policymakers with a valuable opportunity to revisit and improve state assessment systems.