The Affective Expectation Model contends that affective expectations shape affective experience. Specifically, it argues that affective experiences are generally assimilated toward expectations when the two are congruent or when a discrepancy between the two is not noticed. When a discrepancy exists and is noticed, however, affective experiences should be contrasted from the expectation. Two experiments using psychology undergraduates (N s = 122 and 105) were conducted to test whether the individual-difference variable optimism-pessimism moderates these effects. It was hypothesized that optimists, because of their tendency to overlook contradictions, are less likely to recognize when an affective expectation is disconfirmed and thus often assimilate their affective reactions toward expectations. However, it was hypothesized that pessimists, because of their greater sensitivity to contradictions, are more likely to notice when an experience is discrepant from an expectation and thus often contrast their affective reactions from expectations. The results supported these hypotheses.