Equipping teachers to use data is a critical piece of the school improvement puzzle. To help early career teachers (ECT) develop data-use acumen, some districts utilize mentoring supports. While research on mentoring in general is well-developed, research on how mentoring can or does support data-informed practice is not.To address this gap, we examined perceptions about data use in a small Texas district; anticipated differences among comparison groups (i.e., mentors and non-mentors; mentors and ECT) did not emerge. We conclude that without careful selection and supports, mentors may not be able to support data-informed practice to the degree assumed.Equipping teachers to use data in the service of teaching and learning is a critical piece of the school improvement puzzle. Increasingly, policymakers press colleges of education to enact reforms so that teacher candidates graduate with a full slate of skills and enter teaching prepared to engage in robust data-informed practice from "day one" (Duncan, 2010).