The number of international terrorist incidents has been falling since the late 1980's. However, the number of casualties has been rising. In the past, the terrorist groups were organized along Marxist-Leninist lines, tightly controlled with precise political, secular objectives. Some groups thought they had broad public support for their objectives so they constrained themselves in the kinds of acts they would conduct. They wanted to get public attention to their cause but did not want to kill so many people that they alienated the public. Many of the terrorist groups now are working from different motivations. They are acting for ideological or religious-ideological or apocalyptic objectives. People who are operating on those kinds of terms are not necessarily constrained in the number of casualties they want to inflict; in fact they may want to inflict massive casualties. Groups now are increasingly not taking responsibility for attacks, which is another indication that the motive is changing. The new groups are much less hierarchical in their organization; they tend to be ad hoc groups. The challenge is that it is very difficult to get information about them because they don’t have the structure. On the other hand, they tend to be less professional and that gives opportunities after the attack to bring law enforcement into play. The threat of terrorism is increasing and there is a possibility that terrorists will escalate to catastrophic terrorism, which includes weapons of mass destruction and chemical, biological, radiological, or nuclear agents. Recommendations are to give the Central Intelligence Agency a broader mandate to go after terrorist spies; improve the sharing of information between intelligence agencies; increasing the number of interpreters and translators; and increasing intelligence budgets.