For decades, college access programs have aimed to improve college readiness and enrollment rates, particularly for underrepresented populations. Though several published reports have produced comprehensive inventories of college access programs (Gandara, 2001; Perna, 2002; Tierney, Bailey, Constantine, Finkelstein, & Hurd, 2009), no systematic review and meta-analysis of the evidence regarding their effectiveness exists. This paper fills that knowledge gap by systematically gathering, reviewing, and synthesizing the findings on the effectiveness of programs designed to improve college readiness and enrollment for disadvantaged populations. In so doing, it is intended to provide guidance for policymakers and practitioners implementing college access programs, and to identify important gaps in the scientific evidence base that warrant further research. The authors address the following questions: (1) What evidence is available to judge the effectiveness of programs aimed at increasing college readiness and enrollment? (2) What does that evidence base tell individuals about the effectiveness of these programs? More specifically, what are the estimated average impacts of programs on college readiness outcomes within the following four domains: math achievement, language arts achievement, completed coursework, and high school graduation? What is the estimated impact of programs on college enrollment? The review only includes studies of interventions that target students between grades six and 12, or students of comparable ages who have not yet graduated from high school or earned a General Education Development certificate. The review excludes studies in which less than 75 percent of the sample falls within the target population for this review. Given that the authors' results are still very preliminary, they are hesitant to draw strong conclusions at this time. However, two aspects of their preliminary analysis are striking enough to comment on. Measures of completed coursework are the best pre-college predictors of college graduation (Adelman, 2006; Rose & Betts, 2001). They encourage evaluators to consider including these outcome measures in their evaluations of college access programs. The sharp differences in the size of estimated impacts between QEDs (quasi-experimental designs) and RCTs (randomized controlled trials) raise questions about the extent to which QEDs are identifying causal impacts. They must proceed carefully when interpreting the results of the QEDs. (Contains 9 tables and 5 footnotes.)