Since their inception in the late nineteenth century, French left-wing fêtes politiques had always relied on compromises between revolutionary politics and mass communion. They staged an ideal socialist people, while also engaging in a symbolic dialogue with its mundane aspirations. After World War II, the success of a globalized, industrialized mass culture dangerously tipped the scales in the latter’s direction. In the 1960s, this tradition was challenged by the individualistic, anti-authoritarian, and festive facets of the new youth culture, which were embodied in rock popular music, and dramatically displayed in May ’68. Should leftist parties adapt to the new conjuncture, adopt Anglo-American music, and risk losing their identity and purpose? The study of popular music in 1970s partisan festivals sheds light on the productive relations between the French left’s political culture and post-1968 mass cultural politics.