Research suggests that school leaders play an important role in cultivating and developing collaborative data practices by teachers. Although diagnosis and intervention are critical facets of leaders' work to support collaborative data practice development, this work remains poorly understood. Missing from data-use literature is more explicit and holistic attention to diagnostic factors and interventions of importance to the ongoing development of collaborative data practices. To address this knowledge gap, this article integrates largely unsynthesized literature to advance a schema for school leader diagnosis and intervention as a central mechanism for supporting the ongoing development of collaborative data practices. (Contains 4 notes and 1 figure.)