As an instructional coach in a large suburban, high-performing high school, I face many challenges in measuring the impact of my work with teachers on student learning. Our instructional coach model stresses teacher choice to not only work with a coach but also choose a topic on which to focus. This structure meets the needs of the teachers, but it is difficult to measure effectiveness because of the varying nature of the work. I have tried many methods since the start of the program five years ago and realized that, since there is not a direct line from coach to student, most measurements only attempt to capture the indirect link. Teacher surveys can be subjective, and standardized test scores often measure types of student performance