Emphasis on improving student learning has brought increased attention to the execution of schoolwide instructional reforms in general and the use of data by teacher teams in particular as an expected element of a school's instructional reform strategy. With this in mind, the purpose of this article is to focus important attention on the work of school leaders as key developers of collaborative data practices by teacher teams--an area that has received insufficient scholarly attention. Informed by various scholars who have examined organizational change processes and the leadership that underlies organizational changes and drawing from empirical and theoretical data use literature, this article advances a phase-based model of school leadership supports for those tasked with the introduction and cultivation of collaborative data practices in their schools. In so doing, this article provides a testable model for researchers who seek to better understand the work of school leaders in collaborative data contexts. This model should also prove instructive for practicing school leaders as well as those who prepare and develop school leaders.