Collective identity formation is important because it plays a crucial role in sustaining movements over time. Studying collective identity formation in autonomous groups in the Global Justice Movement poses a challenge because they encompass a multiplicity of identities, ideologies, issues, frames, collective action repertoires, and organizational forms. This article analyzes the process of collective identity formation in three anti-capitalist globalization groups in Madrid, Spain, based on 3 years of ethnographic fieldwork. The author argues that for new groups practicing participatory democracy the regular face-to-face assemblies are the crucial arena in which collective identity can form and must be both effective and participatory in order to foster a sense of commitment and belonging. The article raises the possibility that scholars should consider what seems to be an oxymoron: the possible benefits of “failure” for social movements.