Critical Brass tells the story of neofanfarrismo, an explosive carnival brass band community turned activist musical movement in Rio de Janeiro, as Brazil shifted from a country on the rise in the 2000s to one beset by various crises in the 2010s. Though predominantly middle-class, neofanfarristas have creatively adapted the critical theories of carnival to militate for a more democratic city. Illuminating the tangible obstacles to musical movement building, Andrew Snyder argues that festive activism with privileged origins can promote real alternatives to the neoliberal city, but meets many limits and contradictions in a society marked by diverse inequalities.