Since the beginning of the millennium the most important International Organizations, from the UN to the OSCE, passing through the EU, have included in their political and normative agenda the phenomenon of violent radicalization, because they understand that it is one of the great challenges to contemporary security, both for the so-called international community and for internal societies. The processes undertaken by individuals and collectives, which lead them to assume extreme ideologies that justify the use of force, have grown exponentially in quantitative and qualitative terms, and frequently, as indicated by the Spanish Security Strategy of 2017, constitute the previous stage for the establishment of active links with terrorist groups and organizations. Therefore, violent extremism has different signs, since radicalization adopts differentiated forms and is not the exclusive patrimony of any political or religious belief, and in particular its impact on recruitment and indoctrination with terrorist ends, not only constitute a current threat, but which is emerging as one of the great questions of the future with a view to the construction of truly inclusive societies.