Empirical Assessment of Domestic Radicalization (EADR)


Project Details


The Empirical Assessment of Domestic Radicalization (EADR) project uses a mixed-method, nested approach to explore a number of key research questions related to radicalization, including:

  • what are the demographic, background, and radicalization differences between and within the different ideological milieus?
  • are there important contextual, personal, ideological, or experiential differences between radicals who commit violent acts and those who do not?
  • is it possible to identify sufficient pathways to violent extremism? and;
  • are the causal mechanisms highlighted by extant theories of radicalization supported by empirical evidence? 

To address these questions, EADR researchers built the largest known database on individual radicalization in the United States: Profiles of Individual Radicalization in the United States (PIRUS). PIRUS is a deidentified cross-sectional, quantitative dataset of individuals in the United States who radicalized to the point of violent or non-violent ideologically motivated criminal activity, or ideologically motivated association with a foreign or domestic extremist organization from 1948 until 2013 (except for two cases from 2014).

The PIRUS data can be used to explore a number of important aspects of radicalization and extremism in the United States. These include comparisons of ideological and sub-ideological groups, group-based and lone actors, and violent and non-violent extremists. The data can also be filtered by exposure date, age, gender, location, ideology, group, and more to address specific aspects of radicalization in the United States.

This project also includes a subproject:

  • The Profiles of Individual Radicalization in the United States - Foreign Fighters (PIRUS-FF) dataset contains over 100 variables covering all phases - pre-travel, travel, and return - of the foreign fighter cycle at the individual level. The database currently includes information on 288 US-based persons from 1980 through 2016 who have been publicly identified in open sources as having left, attempted to leave, or expressed an interest in leaving the United States for the purpose of supporting the activities or interests of a foreign non-state armed group or foreign regime, and were motivated by religion, ethnicity, or other ideology. The data can be used to explore a number of topics relevant for researchers, policy makers, and practitioners, including the radicalization processes of foreign fighters, the role of travel facilitators, the source of travel knowledge and funds, involvement in terrorist plots in the United States, and extremist groups' support for foreign fighters. 
Primary Findings:

Above all, the EADR project shows that there is no “one-size-fits-all” model of radicalization. Significant background, demographic and radicalization differences are present across the ideological spectrum, and the processes by which individuals and groups come to engage in extremist behaviors are complex, often resulting from a host of psychological and emotional factors that are difficult to model. In particular, this study revealed the following about radicalization in the United States:

  • Significant differences in background characteristics, group affiliations, and radicalization processes exist across the ideological milieus.
  • While the radicalization of individuals on the far left and those motivated by Salafi jihadist ideologies tends to occur in early adulthood, individuals on the far right and those who are motivated by single-issues often radicalize later in life.
  • The conventional wisdom that radicalization is more common among individuals who come from low SES backgrounds and/or lack educational opportunities is generally not supported by the PIRUS data. Most extremists come from middle class backgrounds and have at least some college education. That said, stable employment may decrease the risk that individuals with extreme views will engage in violent behaviors. Stable employment often leads to the development of positive social relationships and places demands on individuals’ time that depress extremist activities.
  • Despite an increase in lone actor behavior in the U.S., radicalization remains a distinctly social process. Group and clique membership rates remain high across the ideological spectrum.
  • While competition between extremist groups in the U.S. is not significantly linked to an increase in violent behavior, group rivalries exist in high numbers on the far right. Research suggests that competition within and between groups can produce disillusionment with extremist movements for certain individuals.
  • Clique membership is high across the ideological spectrum and is linked to an increase in violent behaviors. As peers organize into small, insular groups, common biasing mechanisms, such as group think and in-group/out-group bias, often set in, producing increasingly extreme behaviors.
  • The rates of prison radicalization in the U.S. are low and even across the ideological spectrum, suggesting that it is not a common pathway for most extremists nor is it limited to a particular ideology.
  • Radicalization is typically a long process, often lasting years for individuals, most often those on the far right. Recent evidence, however, suggests that online environments may be speeding up radicalization processes, reducing them to several months in many cases.
  • While documented mental illness is relatively uncommon among extremists, our results indicate that mental health conditions may be linked to higher propensities for violent behavior.
  • Individuals who engage in pre-radicalization criminal behaviors are significantly more likely to attempt or commit acts of violence post-radicalization.
  • Radicalization indicators are often the observable effects of underlying psychological and emotional processes. These processes are complex and are commonly driven by feelings of lost significance and community victimization, as well as the intense need for psychological and emotional rewards. 
  • While it is clear that there is no single pathway to violent extremism, individuals were more open to extremist narratives when they experienced trauma or developed a deep sense of community marginalization. 


For additional information about PIRUS, and findings from START’s analysis of the data, see:

Jensen, Michael, and Gary LaFree, Patrick A. James, Anita Atwell-Seate, Daniela Pisoiu, John Stevenson, Herbert Tinsley. "Empirical Assessment of Domestic Radicalization (EADR)," Final Report to the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice. College Park, MD: START, 2016.​


Project researchers used a combination of quantitative and qualitative methods to generate findings. The statistical investigations of the PIRUS database seek to explore similarities and differences among key individual characteristics across the ideological spectrum and to establish which conceptual components derived from theories of criminology reliably explain shifts from non-violent to violent extremism. Researchers relied upon comparative descriptive statistics and multivariate logistic regression modeling to address those questions, respectively. In addition, researchers compiled 56 life-course narratives of individuals who radicalized in the United States. The narratives were analyzed using fuzzy set/qualitative comparative analysis, which allowed for the appraisal of radicalization mechanisms and made it possible to determine the causal conditions and pathways that are most salient for explaining radicalization to violence. ​ 


Project Period:

Selected Publications