Before watching a fear-arousing antismoking movie, male smokers were administered a placebo pill that was said to have either arousing, tranquilizing, or no side effects. Subjects reported less intention to reduce smoking when they could attribute their arousal to the presumably arousing pill, and greater intention to do so when they expected the pill to be tranquilizing, than when they expccted no side effects. The self-reported number of cigarettes smoked during a two-week period following the experiment decreased in both the tranquilizing and no side-effects conditions, but not in the arousing side-effects condition. The data on subjects' i]ntentions are consistent with predictions derived from Kelley's discounting and augmentation principles and demunstrate informational functions of affective states. Several explanations concerning the differences between intentions and behavior are discussed, and implications concerning strategies for behavior change are explored.