Community expressions-specifically, annual events manifested by groups other than official organizations-can be sites for transmission of crucial understandings of the past that have not achieved representation in formal archives. In this dissertation, to locate the minor narratives of history I analyze a community expression with my focus honed on the ephemeral matter used within it, to imitate and question the reliance in archives on evidence, and explore ephemera as important focus points for the transmission of collective memory. The ephemerally embodied event I studied as an "archive" was the All Souls Procession, a grassroots annual celebration and parade in honor of the dead in Tucson, Arizona. To convey and interpret perspectives from the community enacting and participating in this event through engagement with ephemera, I have used three questions as my guide: How are ephemera used in All Souls Procession events as commemorative community expressions? How has the history of the All Souls Procession been shaped around the commemorative use of ephemera in relationship with recorded documents? And, What are the implications for archives of this case of commemoration through ephemeral community expression? Through qualitative methods of data collection including participant observation, document analysis, and unstructured interviews with thirteen current and former All Souls Procession organizers, I have found two overarching themes in the discourse around ephemeral commemoration in this event: processing the past and softening community boundaries. I found that through these themes of use, ephemera in the All Souls Procession anchor collective memory while constituting community boundaries, meeting a growing need to define and connect "members" of a rapidly expanding "community." With community membership defined as volunteerism in ASP events, ephemera function as iconic draws toward this event, attracting people to a unified theme and then engaging them in constructing it anew, as its ephemeral building blocks must be regularly recreated. Ephemera in this study were also found to help claim ownership and authority for the All Souls community, through occupation of space and memory. Concluding this work are three propositions: First, that in such community expressions, competing "archives" may face off against one another in the online arena, which is both ephemeral and enduring; Second, the use of ephemera as commemorative matter may give a community leverage in controlling records about the past, yet in increasingly transparent ways. Third, as they adapt to the model of participatory archives seen increasingly in the digital archival landscape, users can deploy strategies-forging alliances and "communities" that result in effacements and master narratives, the latter of which are then celebrated as community histories through new cycles of ephemeral commemoration. I ultimately retheorize the archive as collective action to construct, efface, and build community around history, supporting the notion that the more collective, or massive, or spectacular the telling of a story, the better it competes to become a history.