The Center for Research on Education Outcomes (CREDO) assessed the impact of different types of charter school-operating organizations on student outcomes in 24 states, plus New York City and Washington, D.C. The study finds that students in charter schools display slightly greater gains in performance than their peers in traditional public schools, especially students in charter schools operated by certain types of organizations. CREDO’s distinctions between organization types are, however, arbitrary and unsupported by other research in the field. This raises concerns about the practical utility of the CREDO findings. In addition, CREDO researchers made several dubious methodological decisions that threaten the validity of the study. A number of the problems flagged by the reviewers of this study have been raised in reviews of prior CREDO studies. Specifically, CREDO studies tend to over-interpret small effect sizes; fail to justify the statistical assumptions underlying the group comparisons made; and not take into account or acknowledge either the large body of charter school research beyond their own work or the limitations inherent in the research approach they have taken. Because these problems have gone unaddressed in the present study, and because the CREDO researchers have compounded them by creating a confusing and illogical charter organization classification system, the report is of limited if any value in policymaking. Readers should review the report with care.