||The role of dispositional optimism, confidence about experiencing favorable future outcomes, in processing and using health-threatening information in making attitudinal judgments about health-promotion behavior is underexplored. The valence-enhancement hypothesis posits that optimism enhances attitude change following both self-relevant positive and negative messages. We, however, predicted that optimism would increase elaborative processing of and buffer negative affective responses to self-relevant, health-threatening information. In Study 1 (N = 130), undergraduate students consuming caffeinated drinks regularly were presented with either negative or positive hypothetical cardiac consequences of caffeine consumption supported by either strong or weak evidence. Optimism predicted greater elaboration and less negative affect in response to the negative messages, regardless of argument strength. Optimism predicted greater negative thoughts about caffeine use following the negative message. Optimists' greater negativity of thoughts about caffeine use and less negative affective response following the negative messages explained their subsequent attitudes toward caffeine use. These findings confirmed the beneficial roles of optimism in facilitating cognitive elaboration and buffering unpleasant emotional consequences of health-threatening messages, while increasing responsiveness to information about potential negative outcomes involving health. Study 2 (N = 124) tested whether optimists' attitudes toward a recommended health behavior following fear-arousing information varied as a function of personal risk and response efficacy. Undergraduate students were presented with information about Repetitive Strain Injury (RSI) and received false feedback that they were either at high or low risk. Participants were then offered an RSI-prevention training program described as high, moderate, or low in effectiveness. Dispositional optimism predicted enhanced positive attitudes toward the highly effective training, both in the low- and especially in the high-risk condition. When the training was ineffective, optimism predicted greater counterarguments against the fear-arousing information about RSI. Optimists' lower counterarguments against RSI explained their especially positive attitudes toward the highly effective training. Based on the patterns of optimists' responsiveness to potential outcomes of performing recommended behaviors, we propose an extension of the valence-enhancement hypothesis: Optimistic beliefs not only promote attitude enhancements as a function of message valence, but also the valence of the consequences of accepting the persuasive messages.