This research brief summarizes a report by Julian R. Betts, Andrew C. Zau, and Lorien A. Rice, "Determinants of Student Achievement: New Evidence from San Diego" (2003) [ED497299]. Surveys by the Public Policy Institute of California have consistently shown that Californians are concerned about the quality of K-12 public schools and that residents are aware of the wide disparities across schools in both student achievement and school resources. In a unique study conducted in collaboration with the San Diego Unified School District (SDUSD), the second-largest district in California, Julian Betts, Andrew Zau, and Lorien Rice compiled and analyzed a highly detailed, student-level database that enabled them to link factors influencing student achievement in ways that have not been possible with the state-level data generally used in such studies. In "Determinants of Student Achievement: New Evidence from San Diego," the researchers examine resource inequalities across schools, explore trends in achievement, and, most important, provide detailed statistical estimates of the school and classroom factors that most influence student achievement. This research brief summarizes their findings. (Contains 1 figure.)