This opening chapter introduces the purpose of the book—to examine the role of non-state actors as agents of disruption and dissent in public diplomacy—and argues that while examples of non-state actors engaging in political dissent and disrupting the public diplomacy efforts of their respective states are numerous, the phenomenon of political dissent and its role in public diplomacy remains understudied by public diplomacy scholars. The chapter discusses the interconnected nature of dissent and disruption, introduces two definitions of public diplomacy that guide the book, and explains the core premises that inform the book. These include the recognition of agency and diplomatic capabilities of non-state actors, the ability and the right of non-state actors to diplomatic representation, and the idea that disruption is not always (and necessarily) negative and destabilizing as it can produce alternative narratives and create spaces for innovative ideas and practices. Next, the chapter articulates the broad research questions that guide the book, discusses the question of public diplomacy boundaries, and outlines the structure of the book with brief descriptions of each chapter.