The 2001 renewal of the United States' Title I program, which provides federal funds to schools with large populations of low-income students, instituted the Supplemental Educational Services (SES) program in which schools in their third year of failing to make Adequate Yearly Progress (AYP) are required to offer after-school tutoring in core subjects to low-income students, provided by public or private tutoring agencies. States are responsible for implementing, overseeing, and evaluating the SES programs; currently, several states and large local school districts have performed evaluations, with many more in the process of publishing results from statewide SES studies. Although state and district-level provider evaluations have measured SES provider effects on student achievement, there has been no comprehensive synthesis of overall program effects across states, and there is little information that relates provider characteristics to variation in student achievement outcomes. The proposed study will synthesize provider effects reported in the extant body of SES provider evaluations to generate an estimate of the overall effectiveness of the SES policy in terms of improving student achievement, and will seek to identify provider characteristics that are associated with variation in student achievement effects using a fixed effects model.