The College Board reported that, in 2022-2023, about two thirds of $177 billion in U.S. financial assistance awarded to undergraduates through programs sponsored by the federal government, state governments, colleges and universities, philanthropic organizations, and other entities was in the form of grants. While researchers have examined the effects of individual grant aid programs on particular college student outcomes, results have indicated varied effects. Moreover, individual study findings have not been widely synthesized or examined to understand why some programs succeed where others do not. We conducted a comprehensive systematic review and meta-analysis to provide structure to this varied field and better understand programmatic effects. The results of the systematic searching and screening yielded 86 studies, across seven outcome domains, and the meta-analysis synthesized findings from 709 effect sizes from study samples representing 7,656,062 individuals. The meta-analytic results found small but meaningful positive average effects on college enrollment, credit accumulation, persistence, and completion. We cannot conclude from available studies that grant aid increased academic achievement or postcollege labor market outcomes. We also found that grants had larger positive effects on credit accumulation for studies with samples of students at 2-year institutions and studies that combined samples of 2- and 4-year students than for studies with samples of students at 4-year institutions only. Using a relatively new method called an evidence gap map, we illustrate where researchers should focus on producing new evidence.