Objective: This study assessed the impact of Curriculum Infusion (CI) on undergraduates' knowledge, attitudes, and behaviors regarding alcohol and other drug (AOD) use. The related effects of students' perceptions of instructors' credibility and immediacy were also examined. Participants: Participants were 309 undergraduates enrolled in 14 CI classes between Winter 2003 and Spring 2004. Methods: In a pretest-posttest design, participants were surveyed about their substance use, behavioral consequences of substance use, knowledge, and attitudes about alcohol, and their perceptions of the credibility and immediacy of their CI course instructors. Results: Findings indicate that students who perceived their CI instructors as more credible and more immediate were more knowledgeable about alcohol and had healthier attitudes about substance use. Additionally, course size was found to contribute to CI's effectiveness. Conclusion: CI provides faculty with an effective way to make a difference not only in their students' education but also in their health and well-being. (Contains 3 tables.)