In recent years, teacher noticing of children's mathematical thinking has emerged as an important and generative construct in mathematics education (Sherin, Jacobs, & Philipp, 2011). Less is known about ways instructional leaders notice teachers' learning. Between 2011 and 2015, we facilitated professional development (PD) in which coaches, principals, and teachers studied mathematics teaching and learning together. Our initial focus on teacher decision-making was inadequate in meeting instructional leaders' learning needs. We adapted the PD to focus instructional leaders' attention on the work of learning teaching. Analysis of leaders' discourse revealed shifts from noticing teacher characteristics to noticing dilemmas and decision-making within teaching and coaching. Findings suggest new roles for teacher educators and new forms of PD for instructional leaders.