This multi-year study reports on results for New York City Charter Schools through the 2005-2006 school year. As independent entities within the public sector, charter schools vary in their policies and practices. Policies that are unusual in traditional public schools but fairly common among New York City's charter schools include long school years, long school days, long math periods, school uniforms, parent contracts, one or more seats reserved for parents on the school board, and school on Saturday. Charter school applicants include a disproportionate number of black students, both relative to New York City public schools overall and relative to the traditional public schools from which charter schools draw students. On other dimensions of gender and race, applicants reflect the neighborhoods and traditional public schools from which the charter schools draw. A number of measurement problems arise when comparing charter school applicants to students in the traditional public schools on the basis of poverty, disability, and English proficiency. Researchers cautiously conclude that charter school applicants are more likely to be poor than the average New York City public school student and applicants are similarly likely to participate in special education. As of the 2005-2006 round of testing, few charter school applicants were in high school grades and researchers were unable to compute statistically-confident effects for the Regents Examinations. It is expected that there will be sufficient students in the high school grades to show meaningful results in report for future years. Researchers advise that additional years' data is required to detect associations between charter school policies and their effects on achievement. Four appendixes include: (1) Relationship between scale scores and performance levels (Math 2006) ; (2) Relationship between scale scores and performance levels (ELA 2006); (3) Frequently Asked Questions; and (4) Biographies of Research Team. (Contains 9 figures and 16 tables.)