This chapter draws upon normal accident theory and the theory of high reliability organizations to examine the potential impacts of information technology being used as a target in terrorist and other malicious attacks. The chapter also argues that information technology can be used as a shield to prevent further attacks and mitigate their impact if they should occur. A target and shield model is developed, which extends normal accident theory to encompass secondary effects, change, and feedback loops to prevent future accidents. The target and shield model is applied to the Y2K problem and the emerging threats and initiatives in the post-9/11 environment. The model is then extended to encompass the use of IT as a weapon against terrorism.