In the summer of 2012, thousands of teachers across the United States attended several days of professional development workshops. The workshops, which focused on the Common Core State Standards, were part of a Tennessee Department of Education initiative in teacher leadership. The department recruited and trained 200 highly-effective teachers to guide its implementation of the new, more rigorous academic framework, and 13,000 educators learned from these "Core Coaches" in the summer of 2012. The coaches also served as resources for their schools, districts, and regions during the school year. When describing the Core Coach initiative, Tennessee education officials and practitioners paint a picture of cyclical reform. By empowering a select group of coaches to lead the Common Core implementation, the state sought to build a pool of instructional leaders who could support other teachers while becoming better teachers themselves, as well as more influential leaders. Along the way, the thinking went, they would help more and more teachers improve as well, resulting in improved instructional quality across the state. The state's experience highlights the opportunities and challenges of leveraging teacher leadership to drive state-level change. To assist system administrators as they pursue their own teacher leadership initiatives, this profile from Leading Educators and the Aspen Institute details the steps Tennessee took to design and implement its Common Core Coach initiative. Specifically, it examines the initiative's opportunities and challenges within the context of a blueprint for teacher leadership. That blueprint provides a guide for implementing teacher leadership that advances student achievement, and it highlights key phases for system administrators to navigate as they leverage teacher leadership to address their highest priorities. Phases include: (1) Designing for Impact; (2) Leaders are advised to know their content; (3) Measures should be clearly defined before implementation; and (4) Systems should build strategically by designing clear teacher leader roles and responsibilities. Central to the blueprint is the idea that effective teacher leadership marries form with function in order to create transformative change in schools.[This paper would not be possible without the writing and editing contributions of Walter Stern, Chong-Hao Fu, Maria Bourgeois, and Steph Bates.]