School leadership and teacher professional development are two well-defined fields of research within the education literature, yet there is relatively little research that has examined the leadership of teachers' professional development and learning. The study reported in this paper seeks to understand the experience of teachers who have responsibility for leading professional learning in their schools. The first part of the paper describes the Leading Professional Learning program funded by the Victorian Department of Education and Early Childhood Development and designed by Monash University. The program aimed to build teachers' capacity to lead professional learning within their school settings. The program involved a series of workshops for 70 teachers over a period of six months; the design and implementation of school-based Professional Learning Projects; and, the writing of cases that reflected program participants' experience of leading professional learning in their school and their own learning about leadership and professional learning. The second part of the paper analyses the cases written by program participants in order to describe and account for key dimensions of school-based leadership of professional learning. The analysis reveals important facets of the relational and emotional dimensions of leading professional learning in schools. The identification of these dimensions provides important insights for understanding the complexity of teacher-led professional learning, as well as for the design of policy and practice pertaining to leading professional learning.