This article presents evidence that sexually transmitted disease (STD) rates are responsive to increases in alcohol taxes and in the drinking age. The presumed relationship is that a more restrictive alcohol policy reduces alcohol consumption, which in turn decreases risky sexual activity. Reduced-form regressions of STD rates on state alcohol taxes for the years 1981–95 (with controls for state and year) indicate that a $1 increase in the per-gallon liquor tax reduces gonorrhea rates by 2.1 percent, and a beer tax increase of $.20 per six-pack reduces gonorrhea rates by 8.9 percent, with similar though more pronounced effects on syphilis rates. Quasiexperimental analysis of alcohol policy changes supports these findings and offers evidence that increases in the drinking age reduce STD rates among youth. The estimated external cost of alcohol-attributable STDs exceeds $556 million annually, a factor that could be considered in determining optimal alcohol policy.