This study assesses K-12 teachers' beliefs, contextual supports, and actual uses of student data. Results showed that teachers' beliefs, school environments, and engagement in substantive data-driven analyses are associated with their use of periodic and classroom-based data to inform their instruction and communications with instructional coaches, students and their parents. Explicated in this paper are specific recommendations for substantive changes in pre-service and in-service teacher training. Both are of great relevancy in providing teacher training that truly cultivates educators' data literacy, and their capacity to expand opportunity for all students through data-driven practice.