In the first of this four-part series of policy briefs on student data in California, we noted a disconnect in the views of state policy staff and local educators on the need for a statewide longitudinal student data system (see "About This Series"). The local educators we interviewed expressed a readiness to participate in a state data system to gather and track information about student progress in and across schools and colleges. State officials were not convinced that gathering and sharing this information should be a top priority for a variety of reasons, including the challenges of overcoming the politics of gaining agreement across systems and the expense of performing the work and sustaining it over time. In our second brief, we reported that California already collects an expansive set of data about the students in each of its education systems, but that those data are maintained in a maze of separate systems. We identified concerns about the incompleteness and inefficiency of third party data-sharing efforts statewide. We also reported that, given the disconnected data systems and lack of a centralized entity that makes it possible to access, share, and use student data from these different sources, California and its public schools and colleges cannot answer basic questions about student outcomes across institutions. [For Part I of this series, see ED574475; for Part II, see ED584700; and for Part IV, see ED584698.]