Research on radicalisation has come on apace over the last two decades. A major new Handbook on Radicalisation and Countering Radicalisation maps its past, present, and future and finds a field in rude health.


From modest beginnings, research on radicalisation and counter-radicalisation now spans disciplinary and theoretical traditions, and informs an international policy agenda concerned with countering and preventing violent extremism (P/CVE). The work that has evolved around the concept of radicalisation has at times been the focus of fierce criticism and debate, but the concept has undoubtedly transformed the way researchers, policymakers and practitioners think about the causes of terrorism and non-state actor political violence. As the 34 chapters that make up the Routledge Handbook on Radicalisation and Countering Radicalisation reveal, in recent years there have been a number of important conceptual, empirical and practical advances in this vibrant field of research.

Conceptualising radicalisation

While the concept of radicalisation has sometimes been criticised for being unclear, under-theorised or inconsistent, the flexibility of the concept has arguably been a strength, enabling it to be deployed across diverse scales and geographies. Early criticism of radicalisation research has driven efforts to advance theoretical understanding of radicalisation, from more ‘orthodox’ and ‘critical’ perspectives. There are a number of key conceptual take-aways from this research:

  • Radicalisation is a process that can and should be studied at different scales. From individual level processes concerned with how and why people adopt radical views or behaviours, to collective processes of group radicalisation, and mass radicalisation, seeking to explain how publics radicalise in contexts of inter-group conflict.
  • Models and metaphors for radicalisation have become more sophisticated. Early models and metaphors of staircases and conveyor belts have given way to ones that capture better the dynamic and non-linear nature of radicalisation.
  • Research is pushing beyond simplistic binaries between cognitive and behavioural radicalisation. Having been a mainstay of early research on radicalisation, contemporary research is seeking to conceptualise the relationship between ideas and behaviours in ways that describe more effectively the complexity of these relationships.  
  • Radicalisation’s relationship to terrorism and violent extremism has been problematised by work that highlights that very few of those who adopt radical ideas or behaviours go on to engage in terrorism.
  • Intersectional approaches to radicalisation are starting to emerge, although much more work is needed to understand how interactions between gender, ethnicity, religion and class shape radicalisation processes across different settings.

Despite the difficulties associated with researching radical milieus, research designs are becoming more sophisticated and access to data is improving.

Empirical foundations

Research on radicalisation has been criticised for having weak empirical and methodological foundations. Early research on radicalisation was often based on limited empirical research, however this is changing. Researchers have become increasingly adept at finding ways to generate meaningful data about radical milieus and counter-radicalisation programmes. Within the field today there is widespread use of standard social and political science approaches, such as interview-based methods, ethnographic research and surveys, and online research. Nonetheless, limitations and challenges remain:

  • Notwithstanding recent interest in the extreme-right, Islamist radicalisation still tends to be the primary ideological focus of radicalisation research, with the literature also dominated by research in the Global North, and focused overwhelmingly on the present. More research is required across under-researched geographic, linguistic, temporal and ideological cases, both to address basic knowledge gaps and to inform theory building and testing.
  • Researchers are increasingly leveraging comparative approaches to further understanding of radicalisation and countering radicalisation, such as developing insights into why the vast majority of people with similar backgrounds and experiences to those who engage in violence don’t do the same. Nonetheless, such comparative approaches raise significant challenges and questions around how to construct meaningful comparison and what constitutes a credible basis for the shared group-ness of those who do and do not engage in violence.
  • There have been some significant advances in the evaluation of P/CVE programmes, but there is an urgent requirement for more research that documents P/CVE programmes and assesses their effects. There is a particular requirement for work on the experience and effects of participation in these programmes.
  • As researchers continue to strengthen the evidence base on radicalisation and countering radicalisation, a major challenge will lie in keeping pace with and adapting to the impact of geopolitical shifts, increased societal polarisation, and the rapidly changing technological landscape.

Radicalisation research in practice

The chapters in the volume also highlight the extent and vibrancy of debates around the most appropriate ways to carry out research on radicalisation.

Ethics are often at the heart of these debates. These include practical issues associated with engaging directly with those involved in radical spaces and the risks it poses to participants and researchers. Direct engagement with policy planners and practitioners also generates ethical issues around the influence of policy planner/practitioner priorities on research agendas and practice.

The need to safeguard researcher safety and well-being is also beginning to receive welcome and overdue attention.


The research set out in the Handbook demonstrates that although there is much more to be done, understanding of radicalisation and counter-radicalisation has advanced significantly since the early 2000s.

Read more

Baker-Beall, C., Heath-Kelly, C., & Jarvis, L. (2015). Counter-radicalisation in Europe: Critical perspectives. Routledge.

Busher, J., L. Malkki, and Marsden, S.V. (2023). The Routledge Handbook on Radicalisation and Countering Radicalisation. Routledge.

Morrison, J. F., Silke, A., & Bont, E. (2021). The development of the framework for research ethics in terrorism studies (FRETS). Terrorism and Political Violence, 33 (2), 271–289.

Phillips, B. J. (2023). How did 9/11 affect terrorism research? Examining articles and authors, 1970–2019. Terrorism and Political Violence, 35 (2), 409–432.

Richards, A. (2015). From terrorism to ‘radicalization’ to ‘extremism’: Counterterrorism imperative or loss of focus? International Affairs, 91 (2), 371–380.

Schuurman, B. (2020). Research on terrorism, 2007–2016: A review of data, methods, and authorship. Terrorism and Political Violence, 32 (5), 1011–1026.