Abstract: One objection to enhancement technologies is that they might lead us to live inauthentic lives.Memory modification technologies (MMTs) raise this worry in a particularly acute manner. In this paper I describe four scenarios where the use of MMTs might be said to lead to an inauthentic life. I then undertake to justify that judgment. I review the main existing accounts of authenticity, and present my own version of what I call a “true self” account (intended as a complement, rather than a substitute, to existing accounts). I briefly describe current and prospective MMTs, distinguishing between memory enhancement and memory editing. Moving then to an assessment of the initial scenarios in the light of the accounts previously described, I argue that memory enhancement does not, by its very nature, raise serious concerns about authenticity. The main threat to authenticity posed by MMTs comes, I suggest, from memory editing. Rejecting as inadequate the worries about identity raised by the President’s Council on Bioethics in Beyond Therapy, I argue instead that memory editing can cause us to live an inauthentic life in two main ways: first, by threatening its truthfulness, and secondly, by interfering with our disposition to respond in certain ways to some past events, when we have reasons to respond in such ways. This consideration allows us to justify the charge of inauthenticity in cases where existing accounts fail. It also gives us a significant moral reason not to use MMTs in ways that would lead to such an outcome.