The survey focused on whether variations in police activity in screening drivers for drunkenness have any impact on patterns of alcohol consumption among drivers and whether a change in enforcement patterns nationally could reduce the incidence of drinking and driving. The findings indicate that drivers in high-enforcement areas were less likely to drink and drive than those in low-enforcement areas. The survey also showed, however, that this difference could not be explained by variations in perceptions of detection risks. Higher levels of police and media activity locally apparently reduced the incidence of drinking and driving by heightening drivers' awareness of social attitudes against drunk driving and of the dangers of driving drunk. Drivers' judgments of the risks of being caught may be more strongly influenced by national than by local police and publicity efforts. Across the Nation as a whole, drivers' beliefs about police enforcement were an important influence on their use of alcohol before driving. Those who believed that drinking increased their chances of being stopped by the police or who were concerned about the consequences of conviction were less likely to drink and drive. 29 tables and 46 references