CONTEXT: Dram shop liability holds the owner or server(s) at a bar, restaurant, or other location where a patron, adult or underage, consumed his or her last alcoholic beverage responsible for harms subsequently inflicted by the patron on others. Liability in a state can be established by case law or statute. Overservice laws prohibit the sale of alcoholic beverages to intoxicated patrons drinking in on-premises retail alcohol outlets (i.e., premises where the alcohol is consumed where purchased); enhanced enforcement of these laws is intended to ensure compliance by premises personnel. Both of these interventions are ultimately designed to promote responsible beverage service by reducing sales to intoxicated patrons, underage youth, or both. This review assesses the effectiveness of dram shop liability and the enhanced enforcement of overservice laws for preventing excessive alcohol consumption and related harms. EVIDENCE ACQUISITION: Studies assessing alcohol-related harms in states adopting dram shop laws were evaluated, as were studies assessing alcohol-related harms in regions with enhanced overservice enforcement. Methods previously developed for systematic reviews for the Guide to Community Preventive Services were used. EVIDENCE SYNTHESIS: Eleven studies assessed the association of state dram shop liability with various outcomes, including all-cause motor vehicle crash deaths, alcohol-related motor vehicle crash deaths (the most common outcome assessed in the studies reviewed), alcohol consumption, and other alcohol-related harms. There was a median reduction of 6.4% (range of values 3.7% to 11.3% reduction) in alcohol-related motor vehicle fatalities associated with the presence of dram shop liability in jurisdictions where premises are licensed. Other alcohol-related outcomes also showed a reduction. Only two studies assessed the effects of enhanced enforcement initiatives on alcohol-related outcomes; findings were inconsistent, some indicating benefit and others none. CONCLUSIONS: According to Community Guide rules of evidence, the number and consistency of findings indicate strong evidence of the effectiveness of dram shop laws in reducing alcohol-related harms. It will be important to assess the possible effects of legal modifications to dram shop proceedings, such as the imposition of statutes of limitation, increased evidentiary requirements, and caps on recoverable amounts. According to Community Guide rules of evidence, evidence is insufficient to determine the effectiveness of enhanced enforcement of overservice laws for preventing excessive alcohol consumption and related harms.