Entry into terrorist organizations has often been described from an extrinsic perspective, as a biographical rupture. However, the “careers” of activists from illegal Basque far-left and national liberation organizations show continuities, underscored by the players themselves. We used a model developed by Snow and McAdam [2000] to understand the "identity work" that accompanies integration and participation in clandestine groups. Two major forms of identity work characterize entry into the organizations studied: “identity convergence” and “identity amplification”. These results suggest a need to reconsider the heuristic relevance of the concepts of radicalization and tip over into terrorism. They also help clarify the role of both cognitive and affective group identification within the identity redefinition process for the individuals involved.

Over the course of the past decade, “radicalization” has become prevalent as an analytical paradigm to interpret and explain phenomena of political violence, notably in research on jihadist terrorism and Western “foreign fighters” in Syria and Iraq. Thereby, while to some extent opening up new avenues of investigation, the concept also significantly re-shaped the way in which phenomena of political violence were analyzed and explained, focusing analytical attention on processes of cognitive and ideological transformation, mainly at the individual level. The purpose of this article is to examine some of the main strands of development in recent research on radicalization, with reference to and within the context of broader sociological research on political violence as well as reviewing critical debates and recently emerging sub-fields of investigation.