Most evaluations of the effectiveness of correctional education use the distal outcomes of recidivism and post-release employment as the dependent variables (e.g., Aos et al., 2006; Davis et al., 2013). This synthesis sought to determine the effectiveness of correctional education at improving proximal academic outcomes among incarcerated adult participants. A search of the peer-reviewed literature yielded only six studies meeting the selection criteria published from January 2003 to June 2014. Participants in all studies made educational progress as defined by academic and vocational test scores and course credits. The effect sizes in four studies of adult basic education and one study of vocational education were medium to strong (g?=?0.52 to 2.04). One treatment-comparison study of college education demonstrated negligible negative effects, favoring the typical college program (g?=?-0.13 to -0.19). However, students in both conditions improved their standardized test performance and credit accrual. There were no studies examining general educational development (GED) test preparation. The discussion contextualizes the concerns with methodological rigor and addresses the remaining gaps in the literature.