In this research brief, Dr. William Mathis, managing director of the National Education Policy Center (U.S.), summarizes current findings on the likely effect of the widespread adoption of the Common Core State Standards (CCSR). Noting that there is no research on CCSS since it has yet to be implemented, Mathis bases his report on past experience with state standards and the experience of other nations. He identifies two factors that are particularly crucial: “The first is whether states invest in the necessary curricular and instructional resources and supports, and the second concerns the nature and use of CCSS assessments developed by the two national testing consortia.” Mathis also warns and reminds that standards themselves do not teach.