New educator evaluation systems demand a focus on effective teaching and learning while promoting the professional growth of all teachers. By identifying and leveraging the contributions of high-performing teachers as instructional leaders, problem solvers, and decision-makers to lead improvement at the classroom level, the system builds capacity for quality practice at all levels and builds internal expertise. This article describes a collaborative relationship in practice since 2012, between Learning Forward's Center for Results 12 high-profile school systems, and the Bill & Melinda Gates Foundation-funded network, called the "Supporting Effective Teaching Knowledge Development Initiative." The 12 partnership districts have spent the past two years building, modifying, and enhancing the roles and responsibilities of teacher leaders to strengthen the quality of school culture, improve the practice of teaching, and foster a deep commitment to professional growth. The 12 sites participating in the initiative found that it is imperative that teacher leaders be provided sufficient time to engage successfully with the work they are doing, have access to continuous content-based learning, engage with peers to share learning and reflect on successes and challenges, and receive regular feedback that guides revisions to their practice. The article also includes a "Guiding Questions on Teacher Leadership" to begin a discussion on leveraging the knowledge and skills of teacher leaders.