 Objectives: Comparing an expert system based on the Transtheoretical Model of behavior change for patients with at-risk drinking, alcohol abuse or alcohol dependence to a control condition. Methods: About 2,500 screenings among consecutive general hospital patients aged 18 to 64 will be conducted. Subjects fulfilling inclusion criteria severe alcohol dependence excluded will be randomly assigned to one of two conditions with 150 patients each: 1 In the TTM-based expert system group, patients receive an individualized feedback on drinking norms, health-related risks and core constructs of the TTM, augmented by a TTM-based manual. 2 In the control group, participants receive a booklet on health behavior. Outcome assessment will be conducted after 12 months. Outcome variables are alcohol consumption, stages of change progress and utilization of formal help. Expected impact: Findings are expected to provide evidence for a computerized TTM based expert system to be used in primary care. This would be the first international results confirming such an approach in the alcohol field. If a TTM-based expert system would be effective, this could significantly save resources and enhance secondary prevention. Therefore, data are of great public health interest. Relationship to the objective of the collaboration: As in the other studies, empirical data on new proactive approaches to reach underserved populations in the addiction field will be provided. The project will add knowledge on the economical use of interventions. 