This study investigated memory interference in amnestic mild cognitive impairment (aMCI) and normal aging. Participants were 27 young adults, 44 healthy older adults, and 15 older adults with aMCI. Memory interference was examined on the California Verbal Learning Test (CVLT) and on a modified AB-AC paradigm. Despite significant differences in memory performance on the CVLT, interference measures on this test did not distinguish individuals with aMCI and healthy older adults. The AB-AC task involved first learning a list (AB list) of 12 semantically related word pairs (e.g., knee-bone). Twenty minutes later, a second list (AC list) was learned in which the same stimulus words were paired with new response words (e.g., knee-bend). Both lists were repeated until 100% accurate recall was achieved. Finally, participants recalled the first (AB) list. Proactive interference (PI) was greater among older than younger adults, and greater still among individuals with aMCI, but the older and aMCI groups showed similar levels of retroactive interference. This study suggests that PI contributes to the memory deficits seen in aMCI and that tests sensitive to PI may assist in the early identification of aMCI. Memory interventions aimed at alleviating PI may improve memory functioning in individuals with aMCI. (JINS, 2009, 15, 83-93.).