The density of alcohol outlets in communities may be regulated to reduce excessive alcohol consumption and related harms. Studies directly assessing the control of outlet density as a means of controlling excessive alcohol consumption and related harms do not exist, but assessments of related phenomena are indicative. To assess the effects of outlet density on alcohol-related harms, primary evidence was used from interrupted time-series studies of outlet density; studies of the privatization of alcohol sales, alcohol bans, and changes in license arrangements-all of which affected outlet density. Most of the studies included in this review found that greater outlet density is associated with increased alcohol consumption and related harms, including medical harms, injury, crime, and violence. Primary evidence was supported by secondary evidence from correlational studies. The regulation of alcohol outlet density may be a useful public health tool for the reduction of excessive alcohol consumption and related harms.