The ability to remember highly detailed events and discriminate between them is thought to be supported by two distinct but complementary neural computational processes: pattern completion and pattern separation. The current study focused on the process of pattern separation, in which similar memories are assigned distinct representations, thus reducing the overlap between similar inputs. This process is measured behaviorally by tasking individuals with mnemonically discriminating between similar stimuli. The present study addressed the contribution of age and experience, which are difficult to distinguish during development, to pattern separation in adults and 9- to 11-year-old children, in whom this process and its supporting neural substrates are still developing. We examined differences in participant’s mnemonic discrimination of high-experience (e.g., own-race faces) and low-experience (e.g., other-race faces) stimuli. Results indicate better pattern separation overall in adults, and, that level of experience with a stimuli class may moderate age-related differences in pattern separation.