This book is the result of research in Central Java and Yogyakarta which describes the relation and transformation of radicalism into terrorism. Transformation from radicalism into terrorism is not only experienced by an individual but also by radical organization. By understanding the dynamics of such radical organization, it is expected to enable awareness building of various parties to detect any potential threat that diminish the security and integrity of the nation. SETARA Institute developed a hypothesis that intolerance is the starting point of terrorism; and that terrorism is the culmination of intolerance. By exploring public perception via survey and qualitative method, it can be concluded that within the context of Indonesia, in addition to radical and terrorism organizations that show a quite close relation, some of them have experienced the transformation from radical to terrorist.