INTRODUCTION: Although preventable, dental caries remains highly prevalent. Many children do not receive preventive dental services routinely in clinical settings. This review examined the effectiveness of school (preschool through high school) fluoride varnish delivery programs in preventing caries. METHODS: Community Guide systematic review methods were followed. In 2024, databases were searched for studies published through December 2023 on school flouride varnish delivery program effectiveness in increasing fluoride varnish receipt and decreasing caries. Included studies had to be written in English, published in peer-reviewed journals, and conducted in upper-middle- or high-income countries. Data synthesis conducted in 2024 used median RR and interquartile interval (IQI) to summarize findings across studies. RESULTS: Of 31 included studies with 60,780 students, 25 were randomized controlled trials-20 with good quality of execution. Most studies were conducted in low socioeconomic status areas among students at elevated caries risk. School flouride varnish delivery programs reduced caries initiation by 32% (IQI: 21%, 37%) in permanent teeth (19 studies, 25,826 students) and by 25% (IQI: 4%, 37%) in primary teeth (12 studies, 4,304 students). Stratified assessments indicated findings were largely applicable to different settings, populations, and intervention characteristics. Two studies found school flouride varnish delivery programs significantly increased the number of annual flouride varnish applications and 2 found that school flouride varnish delivery program effectiveness was inversely related to socioeconomic status. DISCUSSION: About 30% of states report having no school flouride varnish delivery programs. Possible barriers to implementation include that Medicaid in some states only reimburses dental and medical professionals and does not reimburse non-dental providers for flouride varnish delivered to children older than age 6 years.