Ensuring equitable opportunities and outcomes for all students is a top priority of many educators and policymakers across the globe. Data use can be an important lever for achieving equity, but how this can occur is not well understood. In this article, we draw upon knowledge gained in a decade of in-depth qualitative research to examine the ways in which data use helps to open or close doors for students. We discuss data use practices that influence equity goals: (1) accountability-driven data use and data use for continuous improvement; (2) using data to confirm assumptions and using data to challenge beliefs, and (3) tracking and flexible grouping to promote student growth. Along each of these dimensions, there are active decision makers, complex processes of data use at play, and a great deal of variation both within and across contexts. Ultimately, educators and policymakers are faced with critical choices regarding data use that can profoundly affect students' daily educational experiences and trajectories.