Engrams—physical memory traces resulting from specific experiences—are the central posits of modern memory science. In this paper, I examine engrams through the lens of the theory of mental files. Integrating evidence from a variety of research programs, I argue that engrams exhibit the core functional properties of mental files. I characterize them as discrete informational structures, formed upon individual experiences of events and causally involved in their subsequent recall. Engrams are plausibly structurally complex in a file-like way, consisting of a (...) stable hippocampal index, which may function as an atomic pointer-like component, and a distributed cortical representation of an event’s properties. As such, they afford transmission of content and referential stability during potential content change. Their deployment is constitutive of the capacity for singular reference in episodically remembering particular previously experienced events. This emerging picture of engrams should engender reasonable optimism about the prospects of causal-representational theories of memory. (shrink)