Inhibitory models of working memory efficiency (Engle, 1996; Zacks & Hasher, 1994) assert that individual differences in working memory reflect the efficiency of inhibitory processes that exclude irrelevant information and suppress no-longer-relevant information. The present study examined the implication that these two inhibitory processes operate at consistent levels of efficiency within individuals by examining the correlation between two cognitive inhibition effects, negative priming and negative error priming. Negative priming involves slower response to a probe-trial target that was used as a to-be-ignored distractor on the immediately preceding prime trial. Negative error priming is the phenomenon that errors in a sequence of simple arithmetic trials are unlikely to involve the correct answer to the preceding problem. Participants received distractor-target pairs of simple addition problems and were required to produce the target problem sum. Negative priming was observed for prime distractors, whereas negative error priming was observed in connection with previous targets but not distractors. Consistent with the assumptions of these working memory models, the magnitudes of the two effects were significantly correlated.