Five years ago, California's education data lagged far behind the systems in most other states. However, state leaders and education advocates undertook a purposeful engagement and design process to build a data system that represents the state's values and meets different stakeholders' needs. This case study on California's P-20W Cradle-to-Career Data System is a deep dive into what made the state's process so successful, and provides insights for other state leaders looking to build or improve their own state data system. California's success factors include: (1) Setting a vision and cultivating champions; (2) Codifying and sustaining efforts with legislation; (3) Investing in intentional system design through public engagement; (4) Prioritizing data governance; and (5) Centering inclusion and equity. For California's 5.9 million students, the Cradle-to-Career Data System represents a profound investment in their success and futures. The data system will provide policymakers, leaders, and researchers with trend data and insights for improving education opportunities and outcomes. And tools created with the data in the system will provide educators, parents, and families clarity as they support student decisionmaking through school and career.