Violence/aggression and extreme behavior constitute a very old phenomenon that started with the beginnings of human history. Many writers consider violence (aggression and extreme behavior) as one of the main aspects of human beings. Forms of violence changed according to social, economic, political, and cultural circumstances (Berkowitz, 1993; Gelles, 1999; Ohlin and Tonry, 1989). Currently, the common forms of violence are (1) domestic violence (such as marital violence; violence against women; child, sexual, and physical abuse; and violence against the elderly), (2) demonstrations, (3) strikes, (4) riots, (5) mutiny events, (6) assassinations and assassination attempts, and (7) coup d'etat or attempted coup d'etat (Ismail, 1988,1996; Seiam, 1994; El-Matewally, 1995). In the Arab world, as in other parts of the world, violence became a common phenomenon due to many social, economic, political, and cultural factors. Violence has been manifested in many Arab countries. Daily violent actions and counteractions feed an endless cycle of violence. It is hoped that such conflicts would find a peaceful end. Several Arab research studies, books, and articles have been conducted and written during the last three or four decades to investigate violence/ aggression and extremist behavior. This chapter is a review of Arab research studies on violence/aggression and extreme behavior in the Arab world.