A number of Swedish studies have indicated that it is easy for underaged youths to purchase medium strength beer in grocery shops. The aim of this study was to follow the effects of a community action-based intervention involving information/training of parents, police, and shopkeepers, media advocacy, and monitoring of the sales of beer to underaged youths. Eighteen-year-old students, looking younger, attempted to purchase a six-pack of medium strength beer in grocery shops without showing ID. A questionnaire about perceived availability was distributed among ninth-grade students. Surveys of parental awareness and shopkeepers' attitudes were also conducted. A significant decrease in sales was observed in both the intervention area (from 73% of all purchase attempts to 44%) and in the comparison area (from 60% to 44%). No significant difference was found between the intervention and the comparison areas, in part due to a contamination effect in the comparison area, where similar activities were conducted by the local community. Perceived availability by teenagers did not change. Following the intervention, availability to medium strength beer for young people in the intervention area decreased, but remained high. It is possible that this moderate reduction was due to the intervention but the same is not certain, given the developments in the comparison area. The intervention was primarily based on information and training, whereas a policy of surveillance and sanctions in the comparison area appears to have achieved the same result, with lesser resources. The study also illustrates the feasibility of engaging parents in community action for prevention purposes.