The popularity, demand, and increased federal and private funding for after-school programs have resulted in a marked increase in after-school programs over the past two decades. After-school programs are used to prevent adverse outcomes, decrease risks, or improve functioning with at-risk youth in several areas, including academic achievement, crime and behavioral problems, socio-emotional functioning, and school engagement and attendance; however, the evidence of effects of after-school programs remains equivocal. This systematic review and meta-analysis, following Campbell Collaboration guidelines, examined the effects of after-school programs on externalizing behaviors and school attendance with at-risk students. A systematic search for published and unpublished literature resulted in the inclusion of 24 studies. A total of 64 effect sizes (16 for attendance outcomes; 49 for externalizing behavior outcomes) extracted from 31 reports were included in the meta-analysis using robust variance estimation to handle dependencies among effect sizes. Mean effects were small and non-significant for attendance and externalizing behaviors. A moderate to large amount of heterogeneity was present; however, no moderator variable tested explained the variance between studies. Significant methodological shortcomings were identified across the corpus of studies included in this review. Implications for practice, policy and research are discussed.