Brassroots Democracy demonstrates how Black musicians infused participatory music practice with innovative forms of grassroots democracy. Late nineteenth-century Black brass bands and activists rehearsed these participatory models through collective performance that embodied the democratic ethos of Black Reconstruction. Termed 'Brassroots Democracy,' this fusion of political and musical spheres revolutionized both. Brassroots Democracy illuminates the Black Atlantic struggles that informed music-as-world-making from the Haitian Revolution through Reconstruction to the jazz revolution. The work theorizes the roots of the New Orleans brass band tradition in the social relations grown in maroon ecologies across the Americas. Their fruits contributed to the socio-sonic commons of the music we call jazz today.