In 2010, the National Governors Association Center for Best Practices (NGA Center) and the Council of Chief State School Officers (CCSSO) released the Common Core State Standards (CCSS) for K-12 English language arts/literacy and mathematics. CCSS are a state-led effort to define the knowledge and skills students need to graduate from high school ready to enter college or career training. The standards are evidence- and research-based, informed by the most effective models from states and countries across the globe, include rigorous content, and demand the application of knowledge through high-order skills. As of June 1, 2012, 48 states and territories, the District of Columbia, and the Department of Defense Education Activity had formally adopted both sets of standards. Although the development and widespread adoption by states of the CCSS mark a significant milestone in American education, successful implementation is necessary if students across the country are to realize the benefits. To assess the progress of implementation efforts, the NGA Center interviewed staff in governors' offices and state education agencies from a geographically and politically diverse sample of states. The material from those discussions will inform a series of briefs capturing the trends in state implementation of the CCSS across the country, focusing around the four action areas identified above. The series is designed to provide a snapshot of state implementation activities, recommend promising practices, and call attention to the remaining challenges. This brief focuses on policy levers to build educator effectiveness: (1) preparation programs; (2) licensure/certification; (3) evaluation; and (4) professional development.