In this article, the author describes how his district develops clearly focused professional learning communities (PLCs) and raises its student achievement rating from "one of the worst" to one of the best. Sanger Unified School District in California's Central Valley had been named one of the worst school districts in California. It also had been flagged as one of the first to be named a program improvement district under No Child Left Behind. PLCs provide a structure where student data are reviewed and used by teachers to focus their work and implement best practices that ensure all students learn. The Education Trust-West, an Oakland-based foundation that promotes high academic achievement, recently named Sanger Unified as the third-highest-rated California district of 10,000 or more students in closing the achievement gap. This would not have been possible without the focus and collaborative effort of teachers, staff, and administration working together as a professional learning community.