Formative coaching, an approach that uses student work as the foundation for mentoring and professional development, can help principals become more effective instructional leaders. In formative coaching, teaches and coaches analyze student work to determine next steps for instruction. This article shows how a principal can use the steps of the formative coaching cycle to deepen the conversation following a classroom observation. The article also describes how such one-on-one conversations can be expanded to improve professional conversations about teaching and learning throughout the school. (Contains 3 figures and 1 endnote.)