Under both No Child Left Behind and the Every Student Succeeds Act, school leaders have been mandated to employ data-driven decision-making (DDDM) to diagnose student needs, implement targeted supports, and design school improvements. However, district administrators tasked with developing principals' DDDM capacity face a tough road. The authors present four lessons for doing so based on lessons learned from one urban district's year-long data dashboard intervention for their 200+ principals.