This paper builds on recent calls for a polyphonic approach to study rhetorical uses of the past, to account for multiple and diverse voices that take part in the construction of collective memories. To this end, I explore (multiple) collective memories of a charity’s founding story by tracing how this story was retold in the organization. My findings demonstrate that these recollected stories were localised and embellished within two specific mnemonic communities. I show that two different renditions of the founding story projected social fantasies shared by members of respective mnemonic communities, who used the telling of the story to reaffirm what they think is the core purpose of the organization and their role. This finding is used to discuss how multiple collective memories sustain different identities in the organization. The research further discusses the mutual role of social fantasies in maintaining collective memories in the organization and vice versa.