This article focuses on the "learning leader," exploring "What is professional learning leadership at its core?" Leaders of professional learning come to their responsibility from many roles, from teacher to district administrator, to instructional coach. They set the agenda for professional learning by aligning it to classroom, school, and school system goals for student and educator learning, using data to monitor and measure its effects on educator and student performance. Teacher leaders model, facilitate, advocate for, and support ongoing professional learning within schools. They choose to make a difference, some remaining in their classrooms full- or part-time, and others to serve in one of the new teacher leadership roles. Whether as coaches, instructional facilitators, teacher leaders, or school-based staff developers, highly dedicated and well-prepared teacher leaders work in these roles applying the critical aspects of the craft that are essential to growing their leadership capacity.