Under emerging policy structures in California, the responsibility for school improvement is increasingly placed upon local school districts, with County Offices of Education (COEs) playing a critical support role. In this system, districts are responsible for school improvement, with counties in charge of ensuring quality across districts and providing feedback and support where necessary. Underlying this major policy shift is the idea that local leaders are in the best position to drive real educational improvement and ensure quality across multiple schools and contexts. While a continuous improvement approach involves many changes to the way educational systems work, strategic data use is central to effective implementation. Although there is wide agreement that data are critical to the state's policy vision, many questions remain: What does it look like to use data for improvement in California's context? What data are needed, by whom, and for what purpose, at various levels of the education system? And what can we learn from innovative practice in our state? This paper provides a framework for how data use for improvement is different from data use for accountability and how data should be used by actors at different levels of the system and shares lessons from the CORE Data Collaborative about how data can be used for.