Objectives: To evaluate the effectiveness of a theoretically based and Web-delivered intervention using common course technology for increasing physical activity in a college student sample. Methods: One hundred four students randomly participated in either a Web-based intervention involving 7 theory-based learning lessons or a control group that received minimal physical activity information. Participants reported levels of physical activity and social cognitive theory (SCT) constructs at baseline and after 6 weeks of the intervention. Results: Relative to controls, intervention participants reported increased days of moderate and vigorous physical activity, but few changes in SCT constructs. Conclusions: Web-based interventions can successfully increase physical activity among college students.