This book studies the relationship between music making and social movements using the Solidarity movement in 1980s Poland as a case study. Its central argument is that while music offered a means of performing and commemorating the Solidarity movement as unified, the media of the opposition to state socialism also revealed—and continue to reveal—dissonant discourses on citizenship, culture, and history. The story unfolds along crucial sites of political action under state socialism: underground radio networks, the sanctuaries of the Polish Roman Catholic Church, labor strikes and student demonstrations, and commemorative performances. The musics and sounds of the 1980s are traced through a long history of musical nationalism in East Central Europe and across a transnational media network specific to the Cold War and life under state socialism. By revealing the diverse repertories—singer-songwriter verses, religious hymns, large-scale symphonies, experimental music, and popular song—that played a role across the decade, the book challenges paradigmatic visions of a late twentieth-century global protest culture that place song and communitas at the helm of social and political change. Musical Solidarities draws equally on the methods of historical musicology, ethnomusicology, and sound studies to propose a model for understanding popular, art, and sacred musics alongside one another and in the context of singing, shouting, and listening within the study of political action.