California needs better data on the state's education systems to uncover and remedy systemic, long-standing racial and socioeconomic inequities. To create more just institutions, students, families, policymakers, educators, and advocates need access to quality, disaggregated data that allows them to answer questions about how well the state's public schools, colleges, and universities are serving today's Californians. Indeed, recognizing this state need and the strong constituent support for it, the Governor's office and the state legislature have proposed policies to create a statewide P-16 and workforce longitudinal data system (SLDS) that must be used to advance racial and socioeconomic equity in the state. To meet the needs of families of color and to spur equity-driven, evidence-based action and tools, policymakers must design the system with equity at the forefront. This brief describes five foundational equity principles that policymakers must incorporate in addition to fully funding a SLDS. [This brief was written in collaboration with Mamie Voight.]