While high technology confers many social benefits, it also has important drawbacks. Among these are its vulnerability to certain kinds of accidents, crimes and terrorist attacks. The article examines this vulnerability in some detail and demonstrates the differences in vulnerability of low- and high-tech systems. High-tech systems are vulnerable because they are very sensitive to human error and may depend on the functioning of minuscule parts. The tendency to build larger, highly centralized systems, while producing economies of scale, often compounds these problems. With national and worldwide communication networks, the possibilities for technological crime increase. Technology often provides a distancing between perpetrators and victims which lowers psychological responsibility while it increases the vulnerability of others. Computer hacking and the manufacture of dangerous consumer products are used as illustrations of this distancing. Also, it is shown how the same vulnerabilities that are revealed by accident and carelessness could be intentionally exploited for violent ends. The vulnerability of highly linked communications and power systems and the terrorist use of superweapons are discussed.