Over the past decade, charter schools have been among the fastest-growing segments of the K-12 education sector in Chicago and across the country. This report addresses several key issues related to charter schools using student-level data provided by Chicago Public Schools. Students leaving traditional public schools for charter schools in Chicago tend to look much like the peers they left behind, in both demographic characteristics and student achievement. Transfers to charter schools tend to slightly reduce racial stratification across the schools. Achievement trajectories suggest that, on average, charter schools' performance in raising student achievement is approximately on par with traditional public schools--except that charter schools do not do well in raising student achievement in their first year of operation. Chicago's charter high schools may produce substantial positive effects on ACT scores, the probability of graduating, and the probability of enrolling in college--but these positive effects are solidly evident only in the multi-grade charter high schools (those that include middle-school grades). The large, positive attainment results in Chicago suggest remarkable promise for (at least) multi-grade charter high schools and demonstrate that evaluations limited to test scores may fail to capture important benefits of charter schools. If charter schools (or other multi-grade high schools) have positive effects on graduation and college entry, they may make a substantial, long-term difference in the life prospects of their students. (Contains 11 footnotes and 14 tables.) [Additional support for the research describe in this report was provided by the Stranahan Foundation. This report supersedes ED501834.]