Politics, Grievances, and Protest draws on one hundred interviews and forty years of media coverage to provide a cross-national analysis of student mobilization in Latin America's Southern Cone. The book explains why student protests increased in Chile starting in the 2000s, while decreasing in neighboring Argentina and Uruguay. Its findings show that when democracies persistently ignore social demands, they may indirectly foster protest growth. In such contexts, the absence of meaningful change fuels anti-establishment grievances, encourages social movement innovation, and facilitates processes of radicalization that can spread widely. In contrast, state responsiveness often produces the opposite effect. These findings challenge long-standing theories that link relatively closed political systems and movement radicalization to decreased mobilization and suggest that grievances play a central role in shaping variation in protest activity. This is a Flip it Open title and may be available open access on Cambridge Core.