Objective: To examine substance-related attitudes and behaviours among college students across an academic semester. Design: Pre-post quasi-experimental survey design. Setting: A large University in the Midwestern United States. Method: Surveys were completed by 299 undergraduates enrolled in three courses: drugs and behaviour, abnormal psychology, and normal personality theories. Results: Although students that were enrolled in the drug course were not more knowledgeable about drugs than others at baseline, their knowledge increased by semester's end, while the others' did not. Perceived prevalence of alcohol use was more accurate and became increasingly accurate among drugs and behaviour students. Class enrolment, gender, and baseline substance use were associated with baseline attitudes and behaviours as well as changes over time. Conclusion: This study offers implications for substance use education opportunities on college campuses. (Contains 3 tables.)