In this paper I discuss philosophical and psychological treatments of the question "how do we decide that an occurrent mental state is a memory and not, say a thought or imagination?" This issue has proven notoriously difficult to resolve, with most proposed indices, criteria and heuristics failing to achieve consensus. Part of the difficulty, I argue, is that the indices and analytic solutions thus far offered seldom have been situated within a well-specified theory of memory function. As I hope to show, when such an approach is adopted, not only does a new, functionally-grounded answer emerge; we also gain insight into the adaptive significance of the process proposed to underwrite our belief in the memorial status of a mental state (i.e., autonoetic awareness).What justifies our feeling that the content of awareness refers to the past? How do we determine that our phenomenology is a veridical (or even partly compromised) representation of our past and not, say, a thought or act of imagination? Such questions have vexed philosophers and psychologists for almost as long as attention has been directed toward the (uniquely human; e.g., Suddendorf and Corballis 2007; Tulving 2005) act of recollection.