This paper summarizes the many uses of the California Postsecondary Education Commission's data system and describes work in progress on adding additional data elements. It describes how the Commission is using its Longitudinal Student Data System (LSDS) to examine the movement of students through California's public colleges and universities. The system consists of enrollment and awards data from the University of California, the California State University, and the California Community Colleges. The data include student identifiers provided in accordance with AB 1570 (Ch. 916, Statutes of 1999). The data are being used to develop the performance measures in the accountability framework adopted at the Commission's June 2006 meeting. The Commission uses the LSDS to identify a student's high school for analysis in showing how such measures of student progress as time-to-degree are related to characteristics of a particular high school. This analysis is useful in developing policies that provide students more opportunities to succeed in the university systems. The work in progress to enhance the LSDS by adding more data elements include: admission basis, students' zip codes, and course of study information.