On a recognition memory test, both perceptual and conceptual fluency can engender a sense of familiarity and elicit recognition memory illusions. To date, perceptual and conceptual fluency have been studied separately but are they interchangeable in terms of their influence on recognition judgments? Five experiments compared the effect of perceptual and conceptual fluency on recognition. The results suggest that under standard intentional encoding instructions participants were influenced by conceptual and perceptual fluency manipulations to a similar degree (Experiments 1a and 1b). When the perceptual features of the stimuli were emphasized during encoding, the perceptual fluency manipulation had a stronger influence on recognition memory decisions than the conceptual fluency manipulation (Experiment 2). Enhanced conceptual processing at encoding served to nullify the influence of both perceptual and conceptual fluency on the test (Experiment 3). The nature of the test instructions also influenced the relative contribution of perceptual versus conceptual fluency manipulations to the recognition judgment. In Experiment 4, the influence of conceptual fluency was larger when the recognition instructions were meaning based (a synonym recognition test) than with standard recognition instructions. Collectively, the results suggest that the relative contribution of perceptual and conceptual fluency depends on both encoding and test factors.