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.