DESCRIPTION (provided by applicant): Blood alcohol concentrations (BACs) often are used as indicators of impairment and health-related risk and are usually the specified measure in drinking-and-driving laws. Yet, most drivers have limited understanding of the BAC concept and an inability to estimate their BAC levels inaccurately. Further, attempts to inform drinkers about the risks of heavy drinking - either through providing abstract warnings or through providing specific BAC feedback information - generally have not produced significant reductions in alcohol consumption. Information-based approaches to alcohol harm reduction may fall short of their intended goal because the audiences are not motivated to comprehend or to internalize the information presented. A broad empirical literature on persuasion and information processing underscores the importance of motivational variables in understanding the effects of information. However, theoretical models that describe how risk information should lead to behavioral change have not adequately incorporated motivational elements. The proposed research exploits an opportunity to interject informational and motivational interventions to drinkers in a natural drinking environment and to measure objective changes in the resultant drinking behaviors. The aims of this research are to investigate the effect on drinking of providing warning information and specific BAC information to participants under different motivational conditions. The research also will examine individual demographics and motivational variables that might moderate the effects of the interventions. Participants will be sampled before they drink and provided with varying motivational instruction and informational tools. Some will receive an abstract warning about the risks of high-BAC levels; others will receive a tool that allows them to estimate their BAC levels; and others will be given instructions or incentives to use the information and tools provided to regulate their BAC levels. Participants will be re-sampled as they return from Mexican bars, at which time their actual BAC levels will be measured.