This article describes three types of data that can impact how instructional coaches face the challenges in measuring the impact of their work with teachers on student learning. Descriptions of the three types of data--"shifts in teacher reflective tendencies," "the use of student performance as an indicator of success," and the "contextualization of a change into long-term habits"--have over time provided more valid program evaluations, given timely feedback, and provided the coach with a positive self-reflection of their coaching role.