The study evaluated the long-term impact of a brief motivational intervention (BMI) among college undergraduates mandated to treatment relative to heavy drinking volunteer students. Participants (N = 225; 61% male) were randomized to a BMI (n = 115) or a control group (n = 110). Alcohol consumption (drinks per week, drinking frequency, typical drinks, peak drinks), alcohol-related problems, and readiness to change (RTC) were collected at baseline, 4 weeks, 3, 6, and 12 months posttreatment. BMI participants significantly decreased drinks per week (treatment, [delta]M = 7.33; control, [delta]M = 3.60), typical drinks (treatment, [delta]M = 1.46; control, [delta]M = 0.65), and peak drinks (treatment, [delta]M = 2.16; control, [delta]M = 0.56) relative to controls at 4-weeks posttreatment. Decreases in alcohol-related problems approached significance among BMI participants (treatment, [delta]M = 7.11; control, [delta]M = 5.59; p < 0.10). At 12-months posttreatment, gains for typical drinks and peak drinks were sustained (p's < 0.05). Decreases in alcohol-related problems among the treatment group became significant over time (p < 0.05). Treatment gains for weekly drinking were marginally significant over time (p < 0.10). As expected, no main effect for referral group, or treatment x referral group interaction affected BMI outcomes. Contrary to expectation, receiving a BMI did not increase RTC, nor did RTC moderate BMI outcomes. BMIs appear to be equally effective among mandated and volunteer groups over time. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]