It is well established that financial aid, in the form of grants, increases the probability of enrollment in postsecondary education. A slate of studies in recent years has extended this research to examine whether grant aid also has an impact on persistence and degree attainment. This paper presents a systematic review and meta-analysis of the causal evidence of the effect of grant aid on postsecondary persistence and degree attainment. A meta-analysis of 42 studies yielding 73 effect sizes estimates that grant aid increases the probability of student persistence and degree completion between two and three percentage points, and estimates that an additional $1,000 of grant aid improves year-to-year persistence by 1.2 percentage points. Suggestions for future research and implications for policy are discussed.