This study evaluated the efficacy of an alcohol web-based personalized feedback program delivered in the workplace to young adults. Participants (N = 124) were randomly assigned to one of three conditions: web-based feedback (WI), web-based feedback plus a 15-minute motivational interviewing session (MI), or a control group. Results indicated that participants in the intervention group (WI and MI conditions combined) reported significantly lower levels of drinking than those in the control group at a 30-day follow-up. This was particularly true for participants classified as high-risk drinkers at the baseline assessment. Similar results were found when comparing the WI condition to the control group. No differences were found between the WI and MI conditions, indicating that the addition of a 15-minute motivational interviewing session did not increase the efficacy of the web-based feedback program. Findings support the use of web-based feedback as a stand-alone alcohol prevention program for young adults in the workplace.