What causes an individual to take up violence against civilians for the sake of a political, religious, or social goal? Of course, there are many possible answers to this question. But, one view suggests that narratives may play an especially important role in changing the beliefs, attitudes, and intentions that are precursors to terrorism. There are at least three important implications of this position. First, it is necessary to determine what is meant by terrorism and related terms. Establishing the conceptual boundaries of these terms is a prerequisite to understanding the relationships among them and with narrative communication. Second, it must be established empirically that narrative has the persuasive potency that has been attributed to it. Although narrative has been compared to other forms of evidence, the impact of narrative communication (vs. none) on beliefs, attitudes, intentions, or behavior, has not been determined. Finally, it is important to directly assess the content of narratives that are intended to radicalize. A close examination of the content within terrorist narratives is needed to reveal the targets of belief and attitude change. By determining the persuasive efficacy of narratives and exploring the radicalizing potential of a specific set of extremist narratives, this project advances our knowledge of narrative persuasion processes and helps address the problem of terrorism by approaching it from a communication-based perspective. Chapters 1 and 2 are dedicated to the explication of key terms. Chapter 1 explores the notions of terrorism and extremism, two contested concepts within the literature. Terrorism is defined as the use of violence or threat of violence against civilians to achieve ideological goals. Extremism is defined as a psychological state in which an individual rigidly adheres to an ideology that is characterized by behaviors that marginalize other-minded individuals through a variety of means, up and including the use of physical violence. A model is proposed that suggests that extremism is a risk factor for engaging in terrorism. As Chapter 1 explored the psychological origins of terrorism, Chapter 2 investigates the psychological origins of extremism. This chapter argues that extremism results from a process referred to as radicalization. Radicalization is defined as an incremental social and psychological process prompted by and inextricably bound in communication, whereby an individual develops increased commitment to an extremist ideology resulting in the full or partial assimilation of beliefs and attitudes consistent with that ideology. Thus, it is proposed that those who undergo radicalization are at risk for extremism, and in turn, at risk for engaging in terrorism. After demonstrating radicalization to be a contributing factor for engaging in terrorism in Chapter 2, Chapter 3 illustrates the efficacy of one source with which radicalization can be promoted, narratives. In Chapter 3, meta-analytic techniques are employed to demonstrate that narrative communication positively affects beliefs (N = 4,510; r = .20), attitudes (N = 5,861; r = .21), and behavioral intentions (N = 4,218; r = .19), suggesting that extremist narratives have the potential to contribute to fundamental changes in beliefs, attitudes, and intentions in the direction of those promoted by a terrorist group. Given these results, a close examination of a terrorist group’s narratives would illustrate the beliefs, attitudes, and intentions that might be affected by exposure to those narratives. Thus, Chapter 4 features a theme analysis of the narratives of a terrorist organization, The Animal Liberation Front (ALF). This analysis reveals 10 distinct content themes that are geared towards radicalization. Taken together, the findings of Chapter 3’s meta-analysis and Chapter 4’s theme analysis show how the ALF’s narratives work to promote extremism. Chapter 5 summarizes the findings from the previous chapters and discusses the implications of them. Specifically, this chapter briefly details the ways in which this dissertation may inform future research on narrative communication and strategies to mitigate the impact of extremist narratives on the radicalization process.