What counts as a protest – and what sets it apart from a riot? This chapter introduces these as the key questions animating the book and specifies why they are especially urgent ones for the historically marginalized. It presents the book’s core argument, explaining that our ordinary ideas of protest see it as the material, affectively rational act of a political collectivity and proposes that public audiences make sense of a gathering based on these criteria of materiality, collectivity, and affect. While criterial conventions are the terms of protest and interpretation, however, they cannot determine a gathering’s political legibility. The chapter suggests that legibility is also a matter of relation and mutual attunement between those gathered and their audiences. The chapter distinguishes Unruly Acts from recent scholarship in political theory, explains why its performative framework is appropriate for the questions under consideration, and outlines its critical engagement with J. L. Austin and Judith Butler’s performatives. After describing the reconstructive approach the book adopts, the materials it analyzes, and the instances of public gathering under analysis – the 1992 Los Angeles Riots/Uprising and the 1994 anti-Prop. 187 march in the same city – the chapter concludes by summarizing the book’s plan.