As of August 2011, 44 states and the District of Columbia had adopted the voluntary common core state standards (CCSS) in English language arts and mathematics released in June 2010 by the National Governors Association and the Council of Chief State School Officers. The product of a state-led initiative, the standards are intended to set clear expectations for learning for grades K-12 that are consistent from state to state. The standards also aim to ensure that high school graduates possess the knowledge and skills needed for college and a globally competitive workforce. States are undertaking a variety of activities to implement the CCSS, but if these standards are to guide education reform in the ways envisioned by the adopting states, much work will also need to be done at the school district level. The ultimate responsibility for ensuring that students master the knowledge and skills in the standards rests with districts and schools, and their administrators and teachers. This report by the Center on Education Policy (CEP), an independent nonprofit organization, describes school districts' perceptions about the impact of the common core state standards, their progress in implementing these standards, and the challenges they face in doing so. The information is based on a survey of a nationally representative sample of school districts conducted in the winter and spring of 2011. The survey covered a range of topics, including district budgets, federal stimulus money, education reform, and the CCSS. The information in this report is based on responses to questions specifically about the CCSS from districts that correctly reported their state was one of the 43 states and D.C. that had adopted the standards at the time the survey was analyzed. Other topics addressed in the district survey are covered in a June 2011 CEP report (2011a). The findings in this report provide a snapshot of what districts had done or were planning to do to implement the CCSS standards when the survey was administered in early 2011. Since then, it is likely that states and districts have moved ahead with additional implementation activities. Six key findings about the CCSS emerged from the district survey: (1) Almost three-fifths of the districts in states that have adopted the CCSS viewed these standards as more rigorous than the ones they are replacing and expected the CCSS to improve student learning; (2) Two-thirds of the districts in CCSS-adopting states have begun to develop a comprehensive plan and timeline for implementing the standards or intend to do so in school year 2011-12. Sixty-one percent of the districts are developing and/or purchasing curriculum materials; (3) Adequate funding is a major challenge; (4) About two-thirds of the districts in adopting states cited inadequate or unclear state guidance on the CCSS as a major challenge; (5) Districts appear to face relatively little resistance to implementing the CCSS from parents, community members, or educators; and (6) District or school-level staff participated in various state, regional, or district activities in school year 2010-11 to become informed about the common score state standards. (Contains 4 figures, 4 tables and 1 footnote.)