Objective: The authors assessed short-term effectiveness of a Web-based alcohol education program on entering freshmen. Participants: 3,216 incoming first-year students were randomized to a control or intervention group. Methods: Controls completed a survey and knowledge test the summer before college; 4 to 6 weeks after arrival on campus, they completed a follow-up survey of behaviors and harms followed by an invitation to complete the online course. Intervention students completed the precourse survey and test, the online course, and final exam "prior" to coming to campus. This was followed by a survey 4 to 6 weeks after arrival on campus. Results: Although the intervention group showed significantly higher alcohol-related postcourse knowledge compared to the control group, protective behavior, risk-related behavior, high-risk drinking, and alcohol-related harm did not favor the intervention group, with the sole exception of playing drinking games. Conclusions: Alcohol knowledge alone was insufficient to mitigate alcohol-related high-risk behaviors in this student population. (Contains 1 figure and 6 tables.)