This book investigates the working mechanisms of public opinion in Late Republican Rome as a part of informal politics. It explores the political interaction (and sometimes opposition) between the elite and the people through various means, such as rumours, gossip, political literature, popular verses and graffiti. It also proposes the existence of a public sphere in Late Republican Rome and analyses public opinion in that time as a system of control. By applying the spatial turn to politics, it becomes possible to study sociability and informal meetings where public opinion circulated. What emerges is a wider concept of the political participation of the people, not just restricted to voting or participating in the assemblies.