Repeating a single-prime stimulus as a target to respond to usually facilitates responses. However, sometimes, prime repetition slows the responses and produces the single-prime negative priming effect. In this study, the distractor set hypothesis was proposed as a mechanism of attentional control that can contribute toward single-prime negative priming. In Experiments 1a-1d, an integrated Stroop task was used. The results showed that the prime produced negative priming only when it matched the form of the competing distractors. A separate Stroop task was used in Experiments 2 and 3 and a flanker task was used in Experiments 4a and 4b. In both tasks, the results suggested that a prime produced negative priming when the location of the prime matched that of the distractors. In Experiment 5, alternative explanations including the effects of the prime-to-distractor similarity and the target set were examined. The results revealed that the distractor set, rather than the target set and the similarity between the prime and distractor, could better account for the negative priming effect.