This paper describes the development and impact of an underage drinking reduction program designed and implemented by a South Carolina county sheriff's office with assistance from the county coalition. In December 2017, high school surveys identified family and friends as the alcohol source 82.2% of the time. In Summer 2018, sheriff deputies began visiting with almost all high school seniors, i.e., 1,352 high school senior visits. Deputies reminded parents to not provide alcohol to anyone under 21 years old. School surveys were conducted pre-program (December 2017), during (April 2018 and September 2018) and post-program (April 2020). Comparing the pre-effort results with post surveys found a 22.8% decline in 30-day drinking (p=0.01) and a 23.5% decrease in binge drinking (p=0.07). As described by Holder et al., the results provide the foundation for replication under controlled research conditions.