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How Radicalization to Violent Extremism Occurs in the United States: What Research Sponsored by the National Institute of Justice Tells Us


Author: Allison G. Smith

Date of Publication: June 2018

Journal / Publisher: National Institute of Justice


Design of the study


4 studies: Brandeis University, Indiana State and Victoria Universities, START and University of Arkansas.  The Brandeis University study included homegrown terrorism offenders inspired by or affiliated with al-Qa’ida.  Indicators and evidence for the NYPD four stage process of radicalization framework were coded an then an algorithm was used to determine whether the data supported the sequence of stages. The Indiana State/Victoria University study included individuals who engaged in terrorism but acted alone and did not belong to a group between 1940-2013. A new model of radicalization was developed based on the analysis of various sources of information including biographies, memoirs, journalistic sources, government reports and court documents. The START study include randomly sampled individuals from a larger population meeting inclusion criteria (radicalized in US who espoused ideological motives and acted on these motives.  The University of Arkansas study (quantitative portion) included individuals indicted for violent or nonviolent terrorism-related activities in US between 1908-2013. The Arkansas study included a qualitative analysis of 43 organizations indicted for violent terrorism related activities between 1980-2013. The Arkansas team tested whether role identity theory and framing theory help to explain how individuals and groups radicalize to terrorism.

Number of participants

135; 98; 1475; 465



Type of ‘participant’ 

Lone and group actors; lone actors; lone and group actors; lone and group actors


Mobilization to violence to conduct attacks at home

Key findings 

Lone wolf terrorists frequently combine personal grievances (perceptions of being wronged) with political grievances (perceptions of government entity or political actor related injustices). They then display an affinity with online sympathizers or an extremist group.  Lone wolves are often enabled by others who unwittingly assist them in planning attacks. They often broadcast their intent to conduct attacks.  In addition, they frequently experience personal and/or political triggering events (e.g., losing a job). The internet played some role in individual’s radicalization in just under one half of the cases in PIRUS and being a member of a clique contributed to the radicalization of approximately 42 percent of individuals (Jensen, 2016). The Arkansas study findings suggest the importance of the identity construction process in radicalization to terrorism and the need to understand how groups frame their beliefs.  In addition the conditions that facilitate radicalization to terrorism may vary by organization and type of violent outcome. The 4 NIJ studies highlith the importance of facilitators that may encourage support or contribute to the process of radicalization to terrorism: the role of terrorist belief systems and narratives, identity processes, activities that demonstrate commitment to a terrorist group or cause, connections with terrorists in an offline social network, connections with terrorists via the internet and social media, group dynamics, grievances and triggering events.

Key recommendations 

Trusted information and resources need to be available to assist in the effort of addressing beliefs and behaviors. Prevention and intervention efforts may benefit addressing beliefs that justify violence and helping individuals to develop identities in which these beliefs are not central. Also, dramatic changes in the people with whom an individual associates or increasing insularity among existing groups of friends may be causes for concern. Efforts to prevent or intervene in the radicalization process must take into account both the individuals and those with whom they interact as well as potentially facilitate establishing or re-establishing their relationships with nonextremists. Understanding related grievances and triggering events as well as developing constructive ways to address them may be important components of programs develop to prevent and intervene in the radicalization process. Additional research into the similarities and differences in the processes of radicalization to terrorism among individuals.  Finally, it may be necessary to conduct more research that compares individuals 

Reviewer's Notes

The START study created the Profiles of Individual Readicalization in the United States (PIRUS) databases with characteristics, experiences, behaviorss of more than 900 terrorists and almost 600 nonviolent extremists. At the time of writing this overview, they are in the process of developing life-course narratives for 110 individuals in the database from unclassified, secondary sources (newspaper, court records, biographies and government sources).


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