Three conditioned suppression experiments examined the Hall-Pearce (1979) negative transfer effect in rats. Experiment 1 replicated the effect: CS-US[subscript weak] pairings retarded subsequent fear conditioning to the CS as a result of CS-US[subscript strong] pairings. The size of this retardation was less than that produced by non-reinforced CS presentations (latent inhibition). When the magnitude of the US[subscript weak] was reduced in Experiment 2, the Hall-Pearce effect was greater than latent inhibition. Experiment 3 confirmed the findings of the two previous experiments, and demonstrated that magnitude of the Hall-Pearce negative transfer effect is inversely related to the magnitude of the US[subscript weak]. From these findings it is suggested that the Hall-Pearce effect consists of a balance between a positive transfer of associative strength, and negative transfer based on CS- and US-preexposure effects.