The Introduction previews cycles of silence theory, which seeks to explain how criminal groups constrain citizen cooperation with the police. The Introduction focuses on laying out the book’s central contributions. Theoretically, the book provides a new explanation for how criminal groups prevent cooperation with the police, highlighting the role of their violence in suppressing perceived norms favoring cooperation. The theory speaks to the political science literatures on state-building, political conflict, and criminal governance as well as literatures from other social science disciplines including criminology. Methodologically, the study bridges research divides between the Global North and Global South by testing the theory in both regions. The study also employs realistic survey experiments including a virtual reality–based survey experiment. Finally, the Introduction puts the study into perspective: While the book’s focus may be centered around the effect of violence, the violence should not be interpreted as a defining feature of communities that endure criminal groups.