Objective: The present study reports on the results of a 2.5-year college-wide, coordinated intervention that was implemented from June 2007 to December 2009 to reduce the amount and frequency of students' alcohol consumption. Design: Quasi-experimental study using a one-group (freshmen living on campus) pretest/posttest design ("N" = 6,815 in 2007-2008 and "N" = 7,550 in 2008-2009) with a pseudo comparison group (non-freshmen living off campus). Setting: Indiana University-Bloomington, USA. Method: The social-ecological framework, a multi-tiered strategy that considers the individual, the social milieu, and the environment, was used to guide the selection and implementation of interventions in a university setting to target individuals, the student population, the college, and the surrounding community to reduce high-risk drinking. Freshmen, who were mandated to live on campus, comprised the intervention group while non-freshmen living off campus comprised the pseudo comparison group that received only the environmental-level intervention. Results: A larger decrease was observed in the amount and frequency of alcohol consumption in freshmen than in non-freshmen for the intervention period (mean drinks consumed per week: -15.9% versus -7.5%; percentage of students who drank at least once a week: -17.5% versus -6.7%; and binge drinking: -12.2% versus -1.0%). Conclusion: An ecologically guided campus-wide intervention that is multi-tiered appears to be effective in reducing drinking behaviour.