The Implicit Association Test is a paradigm designed to assess individual differences in implicit cognition. The goal of this report was to examine the reasons for discrepant effect magnitudes obtained with two presumably interchangeable versions: Picture-IAT (P-IAT) and Word-IAT (W-IAT). We show that this discrepancy is due to the relation between stimuli and referent category: the level of representation (LR) at which a stimulus represents an intended category. Experiment 1 replicates the discrepancies found in previous research. Experiments 2–4 show that increasing the LR of stimuli increases the IAT effect. LR affects the magnitude of the IAT effect even when modality and other features of the stimuli are kept constant. The utility of LR for future investigations examining the IAT paradigm is discussed. Copyright © 2009 John Wiley & Sons, Ltd.