Past research on the desirability bias and on bracing for bad news has focused on the potential influence of outcome desirability on people's stated expectations. The present studies examined its influence on behavior—that is, what is done in anticipation of, or preparation for, an uncertain outcome. In five studies, the desirability of possible outcomes for an event, which was uncertain and uncontrollable by the participant, was manipulated, and preparation behavior was measured. Study 1 used a hypothetical-events paradigm. Studies 2 and 3 involved a computer activity in which behavior was tracked on a trial-by-trial basis. In Studies 4 and 5, the uncertain event was the ending of a videotaped basketball game. Rather than exhibiting bracing or a reluctance to tempt fate, participants tended to behave in a manner consistent with an optimistic desirability bias. In a subset of studies, predictions and likelihood judgments were also solicited; the differential effects of outcome desirability on these measures are discussed. Copyright