This introductory chapter argues for a reconsideration of protest music, expanding its scope beyond songs with explicit political lyrics. It situates the recent proliferation of protest music studies within the intensification of global social movements since 2009 and disciplinary shifts in music and social movement studies. Moving beyond a narrow focus on protest music’s communicative functions, the authors propose examining its affective force, pragmatic effects, and organizational role in collective action as well. The introduction outlines the Handbook’s key themes—issues of definition, historical memory, voice, social organization, spaces of protest, and intertextuality—and calls for cross-disciplinary dialogue to generate new insights into the complex ways music and sound intersect with activism. That protest music continually adapts to changing political struggles also means that efforts to define it will necessarily be provisional, requiring that the study of protest music be as open-ended and flexible as its object.