The association between sedentary behavior and an increased risk of cardiovascular disease is well known and validated. Unfortunately, most Americans remain completely sedentary or are irregularly active. Research indicates that theory-based behavioral interventions are efficacious for increasing physical activity, but many interventions require personal contact and cannot be easily disseminated. Recent studies suggest that Internetbased physical activity behavioral interventions are comparable to previously established efficacious physical activity interventions. As such, the Internet may offer researchers and clinicians a viable tool to help promote and disseminate a physical activity intervention that can be used to effectively increase physical activity and ultimately reduce cardiovascular disease risk.