This work aims at analyzing the grounds and the ways in which terrorist behavior develops and settles. The contents are structured according to a global approach which proves useful in helping to explain and predict violent actions by terrorists. More specifically, this paper aims to answer the following questions: What is aggressiveness? What is violence? What is terrorist violence? And which mechanisms and series of psychological processes lay behind these phenomena? Hence, we first operatively define the concepts of aggressiveness and aggression in connection with specific cognitive, emotional and behavioral stages within a personal crisis framework. In order to achieve this, different psychological models are applied. Then, from a theoretical perspective, we tackle the sequential progression of the elements and variables which define the concept of violence in general terms and, more specifically, those concerning terrorist violence. Furthermore, the role of ideology is reviewed by studying the processes which take part in the development and settlement of terrorists’ violent behavior.