Collective effervescence plays a foundational role in the generation of society. Both the canonical explication of this concept, Émile Durkheim’s Elementary Forms of Religious Life, and current literature on the topic, are unable to distinguish between two plausible causes of effervescence: shared affiliation or collective action. This study reports a case of collective effervescence in which much of the assembled group had no prior affiliation. This finding proves that shared affiliation is not a necessary condition for effervescence, and supplies evidence (...) for the hypothesis that collective action, not shared affiliation per se, is the source of effervescence in general. The evidence is a detailed ethnographic and in-depth interview study of the Wisconsin Uprising of 2011. (shrink)