This study tries to figure out the impact of group dynamics on terrorist decision making by exploring the nature of terrorist organizations. This study shows that preconditions of terrorism prepare a fertile condition for terrorism and specific precipitators such as anger and hate motivate certain individual's especially young people to join terrorist organizations. It also shows that terrorist organization usually try to recruit their members from the similar places, where the economic, political, and social deprivation are at most degree. The study also investigates the reason that lies behind terrorism. It suggests that provocative situational context is a first vehicle for terrorism, the impact of group dynamics has more implications than external factors. Since psychological progression toward terrorism occurs inside the organization, group think process may moderate the importance of provocative situational context. There is a direct relation between provocative situational context and group terrorist organization.