Brief motivational interventions (BMIs) for young adult alcohol abuse are among the most cost-effective preventive care measures, yet there has been relatively little theory-based research aimed at improving their efficacy and identifying mechanisms of change. Based on research indicating that low-levels of substance-free reinforcement is a risk factor for poor BMI response, this research team developed and pilot tested a supplemental session to traditional feedback and MI-based alcohol interventions. This session directly targets the behavioral economic mechanisms of substance-free reinforcement and delayed reward discounting by encouraging the development of and commitment to academic and career goals, and by and highlighting the impact of day-to-day patterns of heavy drinking and academic engagement on these goals. A pilot trial (R21AA016304) found that a two session (alcohol BMI + Substance-Free Activity Session; SFAS) intervention resulted in significantly greater reductions in alcohol problems (p = .01, db= .52) relative to a two session (alcohol BMI + Relaxation) active control condition. The BMI + SFAS was also associated with significantly greater reductions in heavy drinking for participants with lower levels of substance-free reinforcement at baseline. This was the first controlled study to demonstrate that a supplement to traditional BMIs can improve outcomes. The current proposal would improve and more extensively evaluate the efficacy of the SFAS in a randomized 3-group (BMI + SFAS vs. BMI + Relaxation Training vs. Assessment only) trial with 425 first and second year college students (projected 50% female and 20% minority) who report recent heavy drinking recruited from two large public universities. The results will determine whether the SFAS enhances the efficacy of a standard BMI while controlling for total contact time. Drinking and substance-free activity outcomes will be assessed 1, 4, 12 and 16 months post-intervention. It is hypothesized that at follow-up BMI + SFAS participants will report significantly lower levels of drinking and alcohol-related problems, and higher levels of constructive substance-free activities, than BMI + Relaxation and assessment only participants, and that the predicted advantage for BMI + SFAS will be mediated by increased participation in substance-free activities and reduced delay discounting. It is further hypothesized that the BMI + SFAS intervention will be more effective for participants who report high baseline alcohol reinforcing efficacy (measured using demand curve and proportional substance-related reinforcement measures) and greater delayed reward discounting than those who report low reinforcing efficacy and delayed reward discounting. This study will also evaluate the economic costs and benefits associated with the BMI + SFAS intervention relative to an active control condition. Should this behavioral economic supplement demonstrate efficacy and cost-effectiveness then clinicians would have a more effective modality for attempting to reduce alcohol use in young adult drinkers, and administrators would have an economic rationale for adopting the intervention in their universities.