This case study examines how one school district in California scaled a structured, data-driven approach to teacher collaboration to improve instruction and student outcomes districtwide. Over the last 8 years, Chino Valley Unified School District (CVUSD) has implemented the Professional Learning Community (PLC) at Work model across all schools in the district, strengthening teacher leadership, deepening teachers' use of student data to inform instruction, and fostering sustained collaboration among educators--all of which have contributed to notable gains in student achievement. The district's ability to scale the model was anchored by district leadership and their partnership with the teachers' union, which helped launch and sustain the district's focus on improving teaching and learning, despite disruptions due to COVID closures and contentious local school board politics. As California continues to prioritize learning recovery and equity, CVUSD's experience illustrates how districts can build coherent systems that strengthen teacher collaboration, enabling educators to work collectively to advance student learning.