This 5-year mathematics professional development project involves 27 elementary teachers prepared and supported as Elementary Mathematics Specialists (EMSs) in high-need urban schools. They complete a university's K-5 Mathematics and Teacher Supporting & Coaching Endorsement programs and participate in Professional Learning Communities and individual mentoring. Described here are data collected at the end of Year 1, illuminating the ways in which they are engaging in teacher leadership, especially coaching. The EMSs are a distinctive population as informal teacher leaders, with a primary responsibility of teaching students. Central to the project is the university-school-community partnership, with findings illuminating reciprocity with mutual benefits, such as high quality clinical experiences for teacher candidates, coaching for novice teachers, and engagement with families and caregivers. [For the complete proceedings, see ED630210.]