A consortium of researchers dedicated to improving the understanding of the human causes and consequences of terrorism

Patterns of Lone Actor Terrorism in the U.S.

Lone actor terrorists -- or individuals who plan, prepare and commit a terrorist incident without help from others -- are relatively few in number but are proportionately responsible for more incidents in the United States than group-based terrorists, according to a new research brief from the National Consortium for the Study of Terrorism and Responses to Terrorism (START).

While lone actor terrorists made up only 6 percent of all terrorists in the United States, they have been responsible for 25 percent of all terrorism incidents in the country. The new brief explores how lone actors also exhibit different characteristics and behavioral tendencies than their group-based counterparts.

START researchers Brent L. Smith, Paxton Roberts, Jeff Gruenewald and Brent Klein examined the differences in geospatial and temporal patterns between lone actor and group-based terrorists using data from the American Terrorism Study (ATS). Housed at the University of Arkansas Terrorism Research Center, ATS includes information on federal criminal cases resulting from FBI investigations for terrorism or terrorism-related activities.

Among the study’s findings:

  • Compared to group-based terrorists, lone actor terrorists are significantly better educated, more likely to be male and less likely to be married.
  • Lone actor terrorists engage in significantly fewer precursor behaviors --which are any activities relevant to the terrorists’ planning or preparation -- per incident than do group participants.
  • Lone actors and group participants are relatively similar in age, but their respective life spans as terrorists are markedly different. On average, group participants “survive” 370 days from the time they commit their first preparatory activity until the time they are arrested. In contrast, lone actors “survive” in excess of 1,900 days from date of first preparatory behavior to date of arrest.

The full brief, “Patterns of Lone Actor Terrorism in the United States,” is available on the START website. 

This story was updated in June 2015.