This meta-analysis examines the strength of the relationships of ACT® Composite scores, high school grades, and socioeconomic status (SES) with academic performance and persistence into the 2nd and 3rd years at 4-year colleges and universities. Based upon a sample of 189,612 students at 50 institutions, ACT Composite scores and high school grade point average (GPA) are highly correlated with 1st-year academic performance. First-year academic performance emerges as the best predictor of 2nd- and 3rd-year retention. SES is a weak predictor of both academic performance and retention. Moderator analyses of admission selectivity indicate that although the estimated mean validity coefficients for ACT Composite scores and high school GPA vary slightly, the credibility intervals indicate they are valid predictors across levels of admission selectivity. This longitudinal study demonstrates the importance of precollege academic preparation and how success in the 1st year of college strongly influences persistence toward completing a degree.