Attentional selection requires both the enhancement of target stimuli and the suppression of distractors. Target enhancement and distractor suppression have been associated with separable components of the lateralized event-related potential: the target negativity and distractor positivity (Pd). We examined the distractor suppression mechanisms indexed by the Pd. The Pd may reflect mechanisms that guide attention away from distractors during search or mechanisms involved in the subsequent resolution of target features. To determine which of these alternatives was more likely, we had participants view search arrays that contained only a target, only a distractor, or both. The Pd elicited by distractors was substantially larger when the display also contained a target, consistent with the idea that this component reflects a mechanism of distractor suppression activated during the resolution and disambiguation of target features.