Novelty is a pivotal player in cognition, and its contribution to superior memory performance is a widely accepted convention. On the other hand, mnemonic advantages for familiar information are also well documented. Here, we examine the role of experimental distinctiveness as a potential explanation for these apparently conflicting findings. Across two experiments, we demonstrate that conceptual novelty, an unfamiliar combination of familiar constituents, is sensitive to its experimental proportions: Improved memory for novelty was observed when novel stimuli were relatively rare. Memory levels for familiar items, in contrast, were completely unaffected by experimental proportions, highlighting their insensitivity to list-based distinctiveness. Finally, no mnemonic advantage for conceptual novelty over familiarity was observed even when novel stimuli were extremely rare at study. Together, these results imply that novel and familiar items are processed via partially distinct mechanisms, with (at least some facets of) novelty not providing a mnemonic advantage over familiarity.