Collaborative remembering, in which two or more individuals cooperate to remember together, is an ordinary occurrence. Ordinary though it may be, it challenges traditional understandings of remembering as a cognitive process unfolding within a single subject, as well as traditional understandings of memory knowledge as a justified memory belief held within the mind of a single subject. Collaborative memory has come to be a major area of research in psychology, but it has so far not been investigated in epistemology. In (...) this chapter, we attempt an initial exploration of the epistemological implications of collaborative memory research, taking as our starting point the “extended knowledge” debate which has resulted from the recent encounter between extracranialist theories of cognition and externalist theories of knowledge (Carter et al., 2014; Carter et al., forthcoming). Various forms of socially and technologically augmented memory have played important roles in the extended knowledge debate, but the debate has so far not taken collaborative memory, in particular, into account. We will argue that collaborative memory supports a novel externalist theory of knowledge: distributed reliabilism. Distributed reliabilism departs in two important respects from both traditional reliabilism (Goldman, 2012) and updated theories such as extended (Goldberg, 2010) and social reliabilism (Goldman, 2014). First, it acknowledges that belief-forming processes may extend extracranially to include processing performed both by other subjects and by technological artifacts. Second, it acknowledges that distributed sociotechnical systems themselves may be knowing subjects. Overall, then, the main aim of the chapter is to draw out the philosophical implications of psychological research on collaborative memory. But our argument will also suggest that it may be useful to broaden the standard conception of collaborative memory to include not only the sorts of direct interactions among subjects that have been the focus of psychological research so far but also a range of more indirect, technology-supported and -mediated interactions, and it thus has implications for psychology as well. (shrink)