This research brief recaps a study of California charter schools. After a discussion of the key distinctions among charter schools, the brief focuses on the following questions: (1) Who attends charter schools? (2) How does student achievement in charter schools compare with that in conventional public schools? (3) What oversight do chartering authorities provide? and (4) Does the operation of charter schools differ from that of conventional public schools? The study concludes that, in sum, the variety of findings suggest reasons for cautious optimism about charter schools. Classroom-based charter schools are doing as well on average as conventional public schools in reading and math while offering in the elementary grades, at least, a wider range of other subjects. There is reason for concern, however, about the performance of nonclassroom-based charter schools. The brief includes the following recommendations from the study to state policymakers: Enhance the ability of chartering authorities to identify poorly performing charter schools; require chartering authorities to collect and monitor fiscal information from charter schools; provide funding to charter schools equal to that of conventional schools; and investigate the reasons for low-achieving charter schools. (WFA)