Attitudes can be conceptualized in terms of the elementary operations of evaluative categorization and response selection-execution. This article describes a component of the event-related potential that is associated with the first of these operations. Ss were exposed to sequences of 6 traits and performed a dichotomous evaluative categorization task. Evaluative inconsistency was varied by embedding very positive, moderately positive, moderately negative, and very negative traits in sequences containing predominantly very positive traits. Highly and moderately evaluatively inconsistent traits, compared with mildly inconsistent or consistent traits, evoked a larger amplitude late positive potential (LPP) that was maximal over centroparietal regions. Furthermore, extremely evaluatively inconsistent traits evoked a larger amplitude LPP than moderately evaluatively inconsistent traits even though both sets of traits were judged to be negative.