Teacher leadership is the process by which expert educators take on roles at the classroom, school, district, state, or national levels to advance the profession, and improve educator effectiveness in order to increase access to great teaching and learning for all students. To maximize teacher impact on student and school success, accomplished teachers must have defined opportunities to share their professional knowledge and expertise with colleagues. While teachers in some schools do participate in collaborative leadership activities, others work in isolation and have few opportunities to engage in conversation on ways to improve teaching and learning. It is the students who ultimately miss out on the benefit of shared knowledge. One way to increase collaboration is to establish systems of teacher leadership that formalize the sharing of expertise in order to promote professional learning throughout a school or district. Examples could include opportunities to leverage expertise by mentoring, peer observation and coaching, leading engagement with families and communities, and taking on responsibilities for curriculum or school improvement activities.