One of the major challenges facing humanity is understanding the psychosocial mechanisms that underlie radicalization in order to effectively deal with its shift towards violent extremism and terrorism. From a scientific standpoint, there have been major theoretical-conceptual and technical-methodological advances which have led to the development of a significant corpus of evidence-based knowledge on these topics. Nowadays, the challenge posed by coping with radicalization into violent extremism is shifting the priority to preventive approaches geared at improving professional practice and proactive decision-making. This monograph takes stock of the current state of the issue and contains four empirical studies grounded in social psychology in an effort to shed light on some current lines of research and their potential applications in the field of security.