The Common Core State Standards (CCSS) represent the first time that nearly every state has set common expectations for what students should know and be able to do. In the past, each state set its own standards, and the results varied widely. And while states collectively developed these common standards, decisions about the curriculum and teaching practices for reaching them are made locally. In addition, the CCSS differ markedly from most state standards that preceded them. They are tied to college and career readiness, and students who meet the standards are expected to be able to go on to postsecondary education without the need for remedial classes--basic skills courses that are costly and do not confer credit but are needed to bring students up to the level of competency expected for new college entrants. The CCSS are also internationally benchmarked, and match the expectations of the highest-performing nations. As a result of these factors, the standards call for significant shifts from traditional practice in both English language arts (ELA)/literacy and mathematics. This brief will describe the CCSS initiative and its current status. It will discuss how the initiative came about, briefly describe the changes in instruction the CCSS call for, assess the current state of implementation, describe the views of supporters and critics, and discuss some of the keys to ensuring that the standards deliver on their promise. (Common Core State Standards FAQs and a list of endnotes are included.)