Terrorism is all but a new phenomenon. With the emergence of Islamist terrorism on the international level, it has become one of the most frequently discussed security issues of our day. Especially after Islamist terrorist attacks in the United States and in Europe, public awareness of the topic is high and the discussion of appropriate counter-terrorism measures dominates the interior politics of Western countries. At the same time, there is little understanding of the phenomenon and its origins.So far, within the huge amount of literature on terrorism, there is little empirical research, based on testing, as to the roots of terrorism. Especially comprehensive in-depth studies of different aspects of terrorism are rare. As Martha Crenshaw puts it, "the absence of significant empirical studies of relevant cross-national factors is an obstacle to identification of propitious circumstances for terrorism."My dissertation investigates this very issue. After presenting a discussion of theoretical issues, the core contribution of the dissertation is the development of a theoretical model and, based on it, a cross-country analysis of the determinants of terrorism.