The Common Core State Standards (CCSS) in mathematics and English language arts (ELA) outline the knowledge and skills that students are expected to learn throughout their K-12 education in order to be prepared for college and careers when they graduate. As of October 2014, 42 states and the District of Columbia have adopted the standards in both subjects, and one state has adopted the ELA standards only. Districts and schools in CCSS-adopting states have a limited window of time in which to develop or adopt curricular materials, prepare teachers to teach to the CCSS, and prepare principals to provide leadership on CCSS implementation. This school year, many CCSS-adopting states will begin administering new assessments that measure students' progress in learning the content of the new standards. Eventually, many states will use the results of these assessments to meet federal accountability requirements and determine which schools are lowest-performing and must undergo interventions. Teachers and principals will also be directly affected; many states are developing educator evaluation systems that hold these professionals accountable for their students' mastery of the CCSS. The standards will have an impact on students as well. Not only will they be expected to learn and pass tests on more rigorous content, but some states may eventually use student performance on CCSS-aligned assessments as a factor in decisions about college course placement or granting of a high school diploma. To learn more about districts' strategies, policies, and challenges in implementing the CCSS, the Center on Education Policy (CEP) at The George Washington University conducted a comprehensive survey of a nationally representative sample of school districts in states that had adopted the Common Core at the time of the survey in the spring of 2014. CEP previously surveyed school districts about the Common Core in 2011 and surveyed state education officials several times about state implementation of the CCSS, most recently in 2013. This report, one of three based on the 2014 survey, discusses districts' efforts to develop and put in place CCSS-aligned curricular materials and to provide professional development to teachers and principals to prepare them for the standards.