This paper reports an evaluation of a community-based approach to prevent underage sales of alcohol. The interventions focused on (a) enforcement of underage sales laws, (b) responsible beverage service (RBS) training and (c) media advocacy. The interventions were implemented in three experimental communities located in California and South Carolina. Purchase survey data were obtained before and after the interventions in each experimental community and in three matched comparison communities. Logistic regression analyses of the purchase survey data for the individual community pairs and for the combined communities showed that sales to apparent minors were significantly reduced in the experimental sites. The findings indicate that these environmental interventions are promising prevention tools for communities that seek to reduce underage drinking.