The Common Core State Standards (CCSS) were created in response to the shortcomings of No Child Left Behind era standards and assessments. Among those failings were the poor quality of content standards and assessments and the variability in content expectations and proficiency targets across states, as well as concerns related to the economic competitiveness of the nation's future workforce. The CCSS in mathematics and ELA were developed in 2009 by governors and chief state school officers in association with educators and researchers. The standards that they drafted were rapidly adopted in 45 states and the District of Columbia. In addition, two state consortia the Smarter Balanced Assessment Consortium, or SBAC, and the Partnership for Assessment of Readiness for College and Careers, or PARCC were created to develop new assessments aligned to the new standards. In general, there is a good deal of enthusiasm for both the CCSS and the assessments forthcoming from the two consortia. Both major teachers' unions, the National Education Association and the American Federation of Teachers, have endorsed the standards, and polls suggest that teachers are generally optimistic about the potential effects of the standards. Researchers have released a number of studies that have indicated that the standards are of higher quality than most of the state standards they replaced,more coherent from grade to grade than prior standards,10 and capture essential mathematics and ELA content.11 While the PARCC and SBAC tests have not yet been released, both consortia are planning several developments, discussed throughout this report, that would represent improvements over prior state achievement tests. Despite the keenness for the CCSS and forthcoming tests, there are a number of likely challenges to the new standards and assessment systems. The purpose of this report is to outline some of these key challenges and offer suggestions for state and federal policymakers to mitigate them. The assessment challenges addressed in this paper pertain to the following seven areas: (1) Higher proficiency levels; (2) Technology upgrades; (3) Computer scoring; (4) Content coverage; (5) Time investments; (6) Validating uses for expanded evaluation; and (7) Rollout coherence. If the standards and assessments are to produce desired improvements in student outcomes, it is essential that policymakers and the developers of the CCSS assessments attend to the seven challenges. This report also offers several recommendations for assessment and accountability systems in the CCSS era.