This analysis of charter school performance addresses two critical questions: (1) how does the academic performance of California charter schools differ from that of noncharters; and (2) how does the academic performance of different kinds of charter schools vary? This study examined achievement data for charter and traditional public schools with 2005-06 results on the following measures: Academic Performance Index (API), adequate yearly progress (AYP), California Standards Tests (CSTs), and--for high schools only--the California High School Exit Exam (CAHSEE). Statistically significant findings for charter schools include: (1) charter schools managed by charter/educational management organizations outperformed other charter schools; and (2) classroom-based charters had higher math scores than nonclassroom-based charters. Statistically significant findings for charter schools versus noncharter schools include: (1) charter middle schools showed higher performance than traditional public middle schools; (2) charter high schools demonstrated higher performance than traditional high schools on the API, which combines results from multiple subjects; but math scores were lower in charter high schools; and (3) charter elementary schools showed generally lower performance than traditional public elementary schools. This 2007 EdSource analysis indicates that charter schools run by management organizations tend to achieve relatively strong academic results. (Contains 3 figures and 18 endnotes.) [This report was written with support from Noli Brazil. For the 2006 edition of this report, see ED491808.]