Little is known about user behavior toward what we call preventive computer technologies that have become increasingly important in the networked economy and society to secure data and systems from viruses, unauthorized access, disruptions, spyware, and similar harmful technologies. We present the results of a study of user behavior toward preventive technologies based on the frameworks of theory of planned behavior in the context of anti-spyware technologies. We find that the user awareness of the issues and threats from harmful technologies is a strong predictor of user behavioral intention toward the use of preventive technologies. In the presence of awareness, the influence of subjective norm on individual behavioral intention is significantly weakened among less technology savvy users but strengthened among more technology savvy users. Also, commonly strong determinants “perceived ease of use” and “computer self-efficacy” in utilitarian technologies are no longer as significant in preventive technologies. Theoretical and practical implications are discussed.