This paper discusses the importance of developing a terrorism severity index and suggests factors to be considered in doing so. A terrorism severity index would enable the observer to more fully understand why terrorism occurs. A severity index would facilitate the separation of act from fiction in dealing with terrorist threats. It would provide an empirical measure to assess the threat of terrorism from various sources. It would also provide a framework with which to measure societal and government responses to such activities. Because the mass media report and interpret the facts for the public, a severity index should include the factors the media deem important. The index must also include severity measures for the general public and the social control sectors. An index would gain significance by being used in conjunction with an index of appropriate social control response. Fifteen notes, 27 reference figures, and tables are provided.